Yesterday I posted about how everyone should have 3-5 open revolving credit accounts. That isn't always easy to get when you don't have a good credit score. There is a way to do it though.
One of the things I recommend you do to get good credit started is a secured credit card. A secured card works this way, you send the bank a minimum deposit of anywhere from $200 to $300. The bank then opens a savings account for you and deposits your money into it. Then you are issued a credit card with a limit matching the amount you deposited. You will receive statements and pay the bill like a regular card except you are not allowed to touch the money that is in the savings account to pay the bill. You won't get the money back until you either cancel the card or the account goes unpaid and reaches charge-off status at which point the bank uses that deposit to cover the unpaid bill.
Another way to get credit is through merchant accounts. These are accounts through which you can only use the credit at the providers store. Examples would be Macy's, Sears, or Jcpenny's. Some of these accounts can be just as hard to get as a regular Mastercard of Visa, but the merchant account providers I recomend to my clients are pretty close to guaranteed approval.