It depends on your position whether you should preflop raise or not. AA, KK, QQ, AK are no brainers from any position. med/pairs, paint cards can be played for a raise if you are in late position. Some starting hands are folds in early position where they could be good for a raise in late position.

btw: I would argue that AQ is a raise from early position. Some books I have read say to fold AQ when early, call if they are suited.