Agression, or any kind of play for that matter, depends on really who the villain is.
For example, if i'm against an opponent who isn't like to pay me off when i hit a draw, i'll play draws fast. However if i'm against a drooler, ill just call with my draws because they're likely to still pay me when I hit because they're dumb.
Sometimes i'll raise or even c/r TPTK if I know that my opponent is an idiot or plays ultra spewy when faced with aggression.
The point is, and I know it sounds cliche, to play the player. Pay attention to what hand you have an think about what you're opponent might do when faced with a certain action and then act accordingly. If you think he's the kind of opponent that folds all worse and calls/raises with better than TPTK then you're ****ing yourself over when you decide to raise your top pair.
Show some hands where you're having doubts about your aggression.