Or here's a better idea: don't have a credit card at all. They offer no real benefits and plenty of dangers. Don't take my word for it, though:
"I tell every student class I get, high school students, university
students, you know, they'd be better off if they never used credit
- Warren Buffet (Net worth: $44 billion)
Before anyone says anything about using credit cards "wisely" and getting the rewards points, I can save 15% on many kinds of large purchases ($100+) using cash. You won't find a reward system offering that level of incentive. Two recent examples of cash discounts:
After I bought my house I needed a lawnmower and a my wife wanted a new vacuum cleaner. Went to Lowe's and found the ones we wanted. They were $600 combined. Found the manager, stuck five $100 bills in his hand and said "this is what I have, and that is what I need." 16.6% saved.
Bought my daugher a bed recently. Queen box spring and mattress were on sale for $300 but it didn't come with the rails, which they wanted $50 extra for. Went to the bank and got $320 in cash from the bank, walked in, set it in his hand and said, "I need the bed box spring and rails, tax included." He replied, "Sorry man, I can't. I'm already taking a loss on..." Then he stopped mid sentence, looked down at the cash again and said "Hold on. Let me ask my manager." Manager walks over, guy explains what I said, manager looks at the cash and says "Make it happen" 14.3 % saved.
As for purchasing a home, it is a myth that you need a credit score to obtain a mortgage for a home. Lending institutions can do manual underwriting instead of just relying on your credit score. It is a little tougher to do and banks usually have stricter requirements, but based on the information the OP has given in this and other questions, I think he can easily meet them.