1. Buy Pokertracker.
2. ???
3. Profit!
OK, seriously though, your read on a player won't matter that much in terms of overall game. Most tables will have a mix of players, so even though one guy on the table is a rock, ramping up your aggression all the time at that table is not going to win you more money. The key is position, and isolation. Then you can make use of your reads.
In terms of position, this is what you should consider before you even sit down at the table. Is it better to have LAGs on your left or right? What about TAGs? Rocks? Check out bisonbison's
Evaluating Sites/Levels/Games and Tables thread for better info on this concept of relative position. Both absolute and relative position are very important when it comes to taking advantage of your reads.
Now, once you have position, its time for the second part, which is isolation. Your reads on one player aren't as effective if there's other people in the hand. You need to isolate the player you have a good read on, so you can take advantage of your knowledge. This is where you can make significant changes to your game based on reads, ie. calling with more marginal hands if he's a maniac, or folding more marginal hands if he's a rock.
Above all, make sure you don't trust your reads too much, whether they be from Pokertracker or direct observation. Correct play is still correct play, and that won't change no matter what type of player you are up against.