Does it make a difference what I purchase or how often I purchase?
A difference with respect to what, exactly? Your credit score when you make purchases using your credit card?
Your credit utilization rate makes a difference. Timely payments make a difference. The exact items you purchase do not make a difference.
Your credit card company doesn't care what you purchase or how often as long as you stay under your limit and pay them on time. They actually LOVE for you to make purchases because they can charge you interest on any unpaid balance at the end of the month. The main thing to remember is that a credit card is a TOOL. Don't use it as a crutch to purchase what you want if you don't have the cash in the bank. The best way to use a credit card is to pay it off in full at the end of each billing cycle. That way you have the convenience of a card without the interest debt.