Engine, go here:
http://www.fafsa.ed.gov/If you plan on going to school this Fall, get your taxes done as soon as possible, then turn around and appy for fin aid as soon as possible after that...you'll need info on your 2004 income when you apply. It'd probably be handy if you know what school you plan on attending, and if you do, drop by their financial aid department and find out from them exactly what you'll need to do.
Eventually, you'll get an offer of financial aid back. Depending on what you qualify for, this can be Federal grants, and subsidized or unsubsidized loans. Grants are good, of course as they're free money you don't have to pay back. Subsidized loans are the next best thing, as the feds cover the interest on your loan while you are attending school. With unsubsidized loans, the interest starts accruing when you receive your first loan check, and you have the option of paying the interest as you attend school or just tacking it onto the loan - your payments will usually start 6 months from graduation.
You may be asked what financial institution you want your loan to go through, and I'm not sure if it matters all that much who you choose. I've always selected Washington Mutual just because, and the loan still ends up with Sally Mae, which is a good thing. For my friends who have loans they are currently repaying, Sally Mae seems to be very flexible about deferments if you let them know ahead of time that you can't make a payment.
If the offer of aid you get back is pitiful, you do have the option of appealing it, usually based on current circumstances. For instance, if your income this year is substantially less than last year...there are a few certain circumstances they list that you can appeal for, but the fin aid office at your college can let you know about that if/when you feel the need to appeal.
Finally, make damned sure that your aid is in place before school starts. Once you think everything is done, talk to the fin aid office once or twice to make sure you're good to go. The folks at my college's fin aid office are "special" (well, most of them), so I find it good to get an answer about any particular issue from two different people just to make sure it matches up.