Use your credit card as if it were your debit card now.
This is what I do as well. I pay with credit cards then payoff the cards a few times a month.
And if you're looking to maximize your score, do some research on the FICO scoring model because that is what lenders use when granting consumers credit. CreditKarma, Quizzle, FreeCreditScore, etc. are all decent ways to track your progress but don't have anything to do with what your FICO score is. That being said, you need more trade lines to increase your score. Most people in the know of FICO scoring recommend 2-3 credit cards with low utilization, at least one installment loan and eventually a mortgage.