Is that sarcasm? In reality, I don't generaly carry credit cards at all. I do have some, but they are used very sparingly.
Learn the credit card company's tricks. Have a high balance card? Get a great cash advance offer for 6 months? Beware. All your payments go toward the main balance and the great cash advance is untouched and then jumps to high interest after the introduction period. Buy a pair of socks or other purchases? Guess what your paymnets go towards while your cash advance at the higher rate continues to roll over month to month.
If you use a cash advance or other promotion, put the card in a safe and don't touch it. Pay it off. Don't carry the card. If I had only one card, and it was tied to everything, I could not take advantage of great offers when they come up without being taken to the cleaners. Rotate the cards. Use the perks, but know the game. Using them carelessly is very expensive.
Ever have a card company call you to find out why you are not using a card with a 0 balance? I have. Told them their interest rate was too high. I was using other cards instead. Got a much lower competitive rate. Now another card is in the lockbox unused. Can't do this with only one card. Use the leverage.