Actually carrying a balance is good for your credit. But keep it very very small so you dont pay much of a finance charge. Remember that the CC companies dont make any money if you dont carry a balance, and therefore are not likely to open up larger lines of credit with you.
On balances on credit cards. You will take a credit score hit if you exceed (dont qoute me cause I'm 2nd guessing in my head) 50% or is it 60% of your open credit line.
Cole, they will not open up your credit huge on one phone call. If you have $2500 now, they may go to $4000, then after 6 months you may get them to $6k, and so on.
My suggestion would be to get an American Express, and use it for everything. AmEx does not allow you to carry a balance it must be paid in full every month. You earn points this way. My wife and I took a 1 week vacation in California last year 90% paid for with AmEx points (flight, rental car, and hotels). This year we flew to and from Europe, and had 4 nights in a Hilton in Paris covered with points. What do we do to get such points? I run everything I do across my AmEx. I mean everything, except for places that dont take AmEx, and then I scoff at them! ****ers.
Credit cards can be good to build credit, you just have to know yourself, and not think you can splurge just cause you have the open credit line.