Oblivion:Efficient Leveling

Efficient Leveling is getting 10 skill-ups under 3 governing attributes every level, so that on leveling you'll gain +5 in all 3. It is much easier and far less intricate than most believe.

The only way your character's level advances is by gaining ten levels (in any combination) of the character's major skills. On the 10th advance, you reach the next level. Unlike many other role-playing games, when you kill a monster, no experience is gained.  Similarly, when you level a minor skill, no experience is gained.

0 skill increases, then you will get one point for picking that attribute
1-4 skill increases, then you will get two points for that attribute
5-7 skill increases, then you get three points for that attribute
8-9 skill increases, then you get four points
10+ skill increases, then you get five points for your selected attribute

Efficient leveling tips :

- Try not to raise skills by more than is required (over leveling)

- Beware your skills going up more than once even though you only got one "skill increased" message. If you attack with a melee weapon or bow repeatedly, without a break, you can blow right through an extra skill increase. This is especially easy to do at low levels. This can be avoided by taking note of the actual number your skill is before you start raising it.

Why Level Efficiently?
Efficient leveling is not required to play, enjoy, or beat the game. People who enjoy efficient leveling do so because they feel that they are getting the most out of their character, or because it provides a needed edge on harder settings.

Efficient leveling requires managing your character's skills. This means keeping track of your skill point gains. You may want a notepad and pencil to help keep track.

The main focus of Efficient Leveling is getting two/three +5 attribute modifiers each level, with no unused modifiers on any other attributes.

Leveling +5/+5/+5 vs +5/+5/+1

There are two major strategies for raising attributes efficiently.

The +5/+5/+5 strategy focuses on getting the highest attribute point gains possible each level increase. This will result in a more powerful character than other approaches, in the short term. This strategy is the fastest way to obtain a character with 100 in all attributes except luck. This approach requires that you gain 20 minor skill points and 10 major skill points per level, in the three attributes you want to raise.

The +5/+5/+1 strategy focuses on raising Luck. The Luck attribute is unique in that you can only raise it by at most 1 point per level. By raising luck every level, it is possible to get 100 luck by level 51 (46 with the +5 luck from a custom class primary attribute selection, 41 with the thief birthsign, 36 with both). The reasoning for this is that you need to gain 50 luck, which requires 50 level gains past level 1 resulting in level 51.  However, if you choose both the thief birthsign and +5 luck, you will still only be able to max all your attributes by a minimum of level 40 due to the other stats maxing out after luck maxes out.  This strategy is the fastest way to achieve a character with 100 in all attributes. This approach requires you to gain 10 minor skill points and 10 major skill points per level, in the two attributes you want to raise.

It is important to note that most skills are capped during game calculations between 0 and 100, reducing luck's importance to earlier gameplay and extraneous effects such as Arena Betting and Mehrunes Razor's Banishing ability.

Avoiding Over-Leveling
If when you level up you notice that you have +2 or higher modifiers in attributes you are not raising, you have over-leveled.

There are a few key methods to avoiding over-leveling:
Decide in advance which attributes you wish to raise this level.
Avoid training skills unless they support the attribute you want to raise.
Avoid gaining more than 10 points in skills that support each attribute.
Create a new save file each time you level up in case you accidentally do over-level.

Another method is to work out how many skill increases it will take to max out each attribute, then see how many skill increases it will take to get to 100. Chances are, you will have ample skill increases going spare. This also has the benefit of becoming the most powerful character possible.

Athletics can be a problem when leveling efficiently as it is being trained constantly while moving. There are a couple of ways to avoid unintentional leveling of athletics. One, purchase a horse as early as possible and use it as much as you can, as riding a horse does not increase any levels. Two, walk around in sneak mode; if there is no one around, you will not level up your sneak and if there are people around, try to draw attention to yourself by walking in front of them and carrying a torch.  Finally, Athletics goes up fastest early on.  Consider training for Speed immediately, to take advantage of the occasional surprise increase in Athletics.  By the time you get to 100 Speed, you will probably find that your Athletics is going up slowly enough to easily manage.

With all of this in mind, remember that over-leveling will not actually mess up your character unless you over-level in extremity. Any given attribute needs 70 points or less before reaching 100 (save for the female Orc's 25 base Personality), and because the least amount of Skill increases you can have for one Attribute is 180, you can "waste" at most 40 Skill increases and still max out any Attribute. When working on higher attributes, with lower Skills, this margin of error increases to a point where the downsides of over-leveling are negligible.

NOTE: When working with efficient leveling it's easier to work on Speed first as it governs the skills of Athletics & Acrobatics which are two of the most uncontrollable skills, therefore unless you're walking around in sneak mode or riding a horse at all times you're going to be over leveling, and it'll only take about 7-8 levels to max out the attribute depending on your race & sign choices. Besides it doesn't hurt to move a bit faster anyway.

Overcoming the Leveling Problem
Choose your 7 major skills. It is strongly suggested that you choose at least one skill from each of the Attributes (excluding Luck, which does not govern any skills).  A major skill under each governing attribute is desirable because a major skill is easier to train, making it easier to increase that skill's governing attribute. It is also recommended to avoid choosing all 3 skills of a single Attribute as Major skills, as this will leave no room for error in leveling that Attribute.

The   can be useful to keep track of where you are in any given level.
There is also an Android application available to keep track skill increases.
Using the console commands "SDT 10" (SetDebugText 10) allows checking your level progress with the "TDT" (ToggleDebugText) console command. Use "TDT" again to hide debug text.

Class Design
It's a little easier to level efficiently with a custom class, though you can level efficiently with most classes:
Choose major skills you will not level accidentally to avoid over leveling. For example, passive skills like Athletics can go up when you least intend it. Skills like Restoration you may need to use to get yourself out of a sticky situation. Ironically, you will have the most control over your leveling if your major skills are skills you don't depend on using regularly.
Choose one major skill for each attribute. This will help ensure that regardless of what attribute you're raising, there is a corresponding major skill for you to level with.
Luck is a good choice for one of your two favored attributes. Since you can only increase Luck by at most 1 each level, this will help you reach 100 in all attributes 5 levels earlier. 
Endurance is a good choice for one of your two favored attributes. Your maximum Health gain each level is based on your Endurance. For this reason, it's efficient to get your Endurance to 100 as soon as possible to gain the most Health. Having Endurance as a class attribute gets you there one level earlier. It also helps with extra Health as you level, since the +10% of Endurance to Health is fixed and is not retroactive (although the base score of 2 x Endurance   retroactive).
If you want your character to reach the highest level possible, for maximum skill points and Health, then you may wish to take major skills which do not receive a bonus from your race or focus. This is because starting these skills higher means that they can get fewer advancements in total. See Maximum Character Level for more information.

Balancing Playing the Game with Training Skills
You could spend all your time practicing skills and never play the game. It's possible to find a balance between the two.

Here's a strategy that combines playing the game with efficient leveling:
Determine which three Attributes you wish to train for that level. Making this decision is easier in the early stages, when just about any Skill can be raised quickly. Later on, check which of your Skills are close to leveling and then commit a "training day" to those Attributes.
For example, if you see that your Mercantile Skill is close to increasing, it may be a good level to raise Personality. Spend a day in town buying and selling goods and speaking with everyone you meet. Cast Illusion spells while walking around town. Alternatively you may notice your Athletics Skill close to leveling. Go out into the wilderness, run and jump all over the place and fight any creatures you encounter while wearing Light Armor. The only Attribute that should take priority is Endurance, so plan to have that worked into your plan for each level until it reaches 100.
When exploring caves and ruins, commit to using Skills that will level your selected Attributes. It may be necessary to adjust your play style, but most characters should be able to incorporate at least one Skill from each Attribute into their adventuring.
Keep track of your total Skill gains, and when you are near to leveling up, focus on getting those last few points needed to get +5 in your chosen Attributes.
It is a good idea to create a save upon reaching 9 Major Skill increases. This way you can reload and fix any mistakes you may have made for that level.
Don't worry if you level a few Skills that aren't part of your current training session. As long as this not allowed to happen constantly, you will have more than enough Skill points to get each Attribute to 100. The main thing is to be wary of your Major Skill increases.

Ultimately, consider that it is not absolutely necessary to have all Attributes at 100. Some of them (such as Personality and Luck) provide little to no bonus and can be ignored completely. Agility may prove no use to a melee warrior, and most characters can run plenty fast with a Speed of 50 (especially at 100 Athletics). Playing this way allows you to max out your desired Attributes earlier and start enjoying the game quicker.

General Tips
Using a Character Creation Tool can be very helpful in selecting a solid character configuration and determining a full leveling plan to maximize your character's potency.
The page on Increasing Skills provides tips on how to train skills in order to maximize your attribute bonuses.
As you level up, opponents become more difficult to defeat. You should include combat skills in your leveling up strategy or you will find it difficult to defeat opponents when you are at higher levels, as they will be better at combat, while you will not be.  Training Endurance-related skills helps to maximize your character's health.
If you want to keep your enemies weak, you can continue raising your skills at level one without resting to level up. In the same vein, you can also keep your enemies weak and not raise your level by focusing on minor skills. In fact, you can have a powerhouse level 1 character, able to destroy anything that is encountered with a 100 skill in all minor skills. While counterintuitive, this kind of leveling will produce more powerful characters (relative to the game world) than focusing entirely on major skills. You may find a paper and pencil useful for this method, of course, or you'll risk losing track of which skills you've leveled already, and which ones you're working on now.
If you write down all your skill values when you level, you'll always be able to predict what your attribute bonus will be when you rest. The   is useful if you lose track of where you are in any given level.
Most skill increases are based on the number of times you use the skill, not on how great an effect it has.  For example, repeatedly casting 5-point spells has the same skill increase effect as casting the same number of 200-point spells. Therefore, you should train using low-cost spells so that you can cast them more times before having to recharge your Magicka.
Train "passive" skills like Athletics and Acrobatics on low levels, as you should use the advantage of being able to gain +5 to Speed much easier than later on in the game.  Note that two out of three skills for this attribute are trained more or less passively (and as a Heavy Armor character you really don't want to wear light armor just because you missed the opportunity to raise Speed on earlier levels).
If you have not maxed out an attribute, but you have maxed out the skills for it, (and are not playing as a lawful character) then you can allow yourself to be arrested and go to jail, which will lower your skills and give you another chance to raise those last few attributes higher.
 An easy way to check up on your skills is to use the console. First type in   and then toggle it on/off by entering  . The screen that is shown is fairly self-explanatory, and extremely useful.

See also
Leveling
Under Leveling
Increasing Skills
Increasing Attributes