I recommend all of you go to yahoo finance and read some of the articles (at least the ones about credit) by Suze Orman
. She's awesome.
What mansonozz suggested (get a loan and pay it back w/ the loan amount) is something I've read about and some experts recommend doing that (as long as you don't spend the borrowed money...put it in a savings account).
Also, TunedIn is right on...if you have a credit card open for a long period of time, you don't want to close it (according to Suze Orman) because it has your history on it. That being said, I closed one of mine that I had open for 5 years and my credit score is still good. The thing about the ratios is true - they use the ratio of available credit to used credit. Just because you have a credit limit of 10k does not mean you have to use it. I believe most recommend you don't go over 50% of your total limit.
When buying a house, they use a couple formulas regarding your income and monthly payments to decide how big of a loan you can afford, so your income and loans (school, car, credit cards, etc) play a large role along with your credit score/history. When buying a car, they're not nearly as strict w/ the ratio's.
If you're going to get a credit card and pay the payments off every month (as you should), then don't worry about getting a low APR, get a credit card w/ low/no annual fees. Usually there's a trade off: Low annual fees & higher APR or Lower APR and higher annual fees. If you pay the card off, you don't pay interest, so you don't care about lower APR. If you plan to carry a balance, go for the lower APR, which will usually mean higher annual fees.
Personally, I'm 22 (23 next week) and I got my first credit card when I was 16 (my mom has excellent credit, so they offered me one). I've always bought a lot of stuff on credit cards instead of using cash, BUT it's stuff I was going to buy anyway - don't just go spend to be "helping your credit." I buy my gas on credit card, most of the stuff from wal-mart, autozone, and of course the net and then try to pay it off ASAP. You can pay more than once a month, too. If you can only afford the minimum one week, pay it so that it's in on time, but pay more the next week to keep your interest down. However, always try to pay it in full by the due date each month (obviously) to avoid interest.
Last year, I got a $4000 personal loan to put w/ my other money to buy my truck. When she ran my credit score, it came back as 780. 780 is really good, especially for being 22, so I must be doing something right
Also, be sure and pay your other bills on time (phone, etc).
Sorry for the book