you can do anything to your car by yourself....you are the only limit. but some factors to consider iinclude, but are not limited to....tools? aptitude? time? problem solving techniques when you run into problems....
Pick up a decent set of tools for yourself, to include jackstands. Sears usually has some good deals on basic handtools sets, but watch what you pay for...the 200 pc set may include 20 allen wrenches and 15 screwdriver tips.....Pick up some literature on your car like a haynes manual, they'll tell you how to remove most of the components on your car, install your aftermarket goodie in the reverse order...
oneof my favorties...go out to a junkyard and remove some stuff on a practice car, if you break something who cares.
As far as gears, that's the only thing I didn't do myself (time was the only factor preventing me). Pick yourself up a CAI (or make your own), and get some pullies, easy to do, good way to get into getting your hands dirty as a hobby.
Good Luck