Its also good to figure out what kind of budget you have before you make any changes, and how much you plan to spend in the end. It will save money to do things yourself, but there will be more down time where the car is not available.
For example, if you have a long term plan with a fairly good budget I might start out with a switch to Vortec RHS heads, and a roller cam conversion, since that would provide a good basis for later changes. But if you just want quick increases in HP right now I would put my money into a more aggressive flat tappet cam, good headers and exhaust, and a well tuned carb and intake. The catch is that the money you put into the quick upgrades now might be lost later if you switch to better heads and a roller cam later on.