Hey, welcome to the boards,
Well where do you wanna start, Cosmetics, or performance ????
if your going performance, then Exhaust, Intake, Headers, would be a START, you'd need to decided if you wanted to do Turbo, nitrous, or maybe an engine start, Don't get intake or headers, with out decided those first. of course your gonna need to throw in suspension also.
Cosmetics.... Wheels, Drop, Bodykit. Then your on your own.
Here's a useful link .
http://www.2k1civic.com/parts/
Happy Honda'ing