The most significant ones (in somekind of an order, not necessarily exactly from top till bottom):
1) change your desktop system from Gnome (or KDE) to something lighter; for Gnome-like, try XFCE, you'll probably like it (especially the new version). Or if you feel like learning something new, try Fluxbox or WindowMaker (the latter is my favourite, for not-so-obvious reasons). This helps probably the most, since X is the thing that eats up a big deal of your resources.
2) Stop unnecessary services; if you're running sendmail that you don't need, mysql daemon that you don't need or something else that you don't explicitly need, it's good for your resources (and security) to turn them off. Fedora has a graphical utility to do this, you will find it somewhere in the settings menu.
3) If you want to be real tight-a.. then compile your own kernel, and only put in the things you need. Warning: updating kernel will be a headache of somekind (compared to the regular update which is just a click), and if you are not sure which things you need in the kernel, it might be better to leave this off for a while - instead, try to learn it first, do some tests and so on.
Anyway, changing your Gnome/KDE to some other, lighter desktop system will make the best out of it. Plain console runs surely fast on your computer, so it's most of the time just X that's sluggish; see how much your current desktop system and X need memory and other resources and compare the result after you have switched to another desktop thing/window manager - you'll not just see, but feel the result.
Also adding small amount of RAM will boost up significantly.