Garry's Strategy Guides/Priority for each Town Hall

The general order of upgrading when reaching a new TH level
*Laboratory (you can have a troop upgrade going while the lab is upgrading)
*Spell factory/s, especially if this grants another spell slot get it out of the way so you can use spells again
* With one builder try to get down each new building available that doesn't have huge build times, including walls, then you'll be able to easily copy links for base layouts. This changes a little as your TH goes higher. Some things take quite a while and can be left to do later, such as X-Bows, Inferno Towers, Eagle Artillery, etc.
*Walls - Whenever you have excess gold put it into walls, don't leave walls to last.
*Heroes - Whenever you have enough loot prioritise heroes, Royal Champion > Grand Warden > Archer Queen > Barbarian King.
*Army Camps - one at a time
*Clan Castle
* Max one barrack/s, best not to have too many barracks going at once otherwise increased cooking time will slow down farming
*Storages - help boost loot protection and give you enough room for upgrades
*Dark Elixir Drill/s
*Barrack/s - bring the rest of the barracks up to the same level, or just to whatever farming army you're using.
* Eventually bring your defences up to be on the same level as your older ones
** Priority depends on your TH level. Some levels air attacks are huge, but your base isn't strong enough to defend. Some levels you need double giant bombs to defend hogs and miners.
** Generally, the order is as follows - air and ground splash dmg (WT) > splash ground dmg (mort, etc) > air (air defence) > air and ground (archers) > ground (cannons)
*Collectors - Depending how active you are, you can prioritise collectors to get you passive income. If you're an active farmer I'd reccommend going for a more an active offensive approach. If doing collectors upgrade evenly.
*Traps - Situational, Giant Bombs great for stopping Hog Riders and Miners. Air Bombs and Seeking Air Mines for slowing down air attacks.
Basic rules
* Offence over defence - The best you can do is deter raids, never stop them. Best approach is to farm more than you give up.
* Spend excess gold on walls, never leave them last!
* Always keep the lab upgrading, upgrade troops in whatever army you use, early on BArching is very efficient
* Depending on your play style, you can rush TH's and be purely offensive but if it's your first time playing you're only really rushing to get to the grind faster
*If you're participating in Clan Wars always consider the clan and the effect your hero upgrades will have on wars - generally don't participate without your heroes