Where to place a tattoo is, and always should be, your own decision. Don't be influenced by "it'll hurt less there" or "it'll be cooler here", get the tattoo where YOU want it!
General advice on placement is that you should consider what kind of clothes you wear, work and social, whether you would like it to show all the time or only when you want to show it off, and in some cases, the appropriateness of the design itself (i.e. the naked warrior girl might be better placed on the calf than the forearm for those who have to attend PTA meetings or be Soccer Mom/Dads!
Most professional tattoo shops will not tattoo faces. They may tattoo your neck and hands IF you already have a lot of coverage. Do not expect to be able to get your first tattoo on your knuckles at a reputable shop!
There are certain areas of the body where the skin does not cooperate well with tattoos over time, notably the fingers, toes and feet. Hands are constantly exposed to the sun, scuffing and rubbing on things, likewise the feet and toes rub on shoes. This means the skin is tougher in these areas and constantly regenerating so it is likely the tattoo will fade fairly quickly. It will need to be touched up on a regular basis. It may not seem like a problem at first, but on your fifth redo, you might begin to wish you hadn't bothered! Women who are considering having children are advised not to get tattooed on the stomach and local area as the skin stretches so much during pregnancy that the tattoo is often badly damaged.
Some types of SCARRING can be tattooed over, but not all, consult with an experienced artist about this. Surgical scars should be at least 6 months old before they are ready to be tattooed over.