You've got three choices:
1. Don't do anything. You'll be fine unless you really need 2 to 10 GB of hard drive space.
2. Go through and manually remove applications, printer drivers, non-English help files, etc.
3. Do a fresh install that includes only what you want.
I think #3 is the most direct solution and you better learn about what's on your computer in the process. But #1 is completely fine for most people. There's no reason to be parsimonious and leave out apps just to save space unless you just don't care at all about one (for me it's iChat).