1. First of all get to Know which of your accounts are listed on your credit reports.
2. Next thing is you need to Request the copy of your credit report at least once a year from all three major credit agencies.
3. Make sure you take time to Check all the information on report is accurate and match your personal and financial details.
4. Be sure that you Pay all of your credit card, utility and other bills on time and dont worry about paying all the payment at once, you can pay the minimum payment and that will be fine to build the good credit history.
5. If you make sure that you dont go over the credit limit on your credit card, that will be good for your financial situations and for credit history also. Few of your credit card companies allow you to do so as a courtsey, but it is advisable not to do it as it may reflect badly on your credit history if your wont be able to pay the bill ontime.
6. You should cancel your credit cards that you are not using.