The best I've been able to do in maxing the rewards opportunity with a cc while making sure I don't spend more than I can PIF or otherwise afford to rack up on a cc was to go ahead and use the cc to pay for things but deduct each purchase amount in my checkbook register as if I was using my debit card - checking acct. gets low, quit buying stuff. I also tend to actually pay the card multiple times a month so that my online account info for my checking account is more nearly in line with my register.
If how much (or little!) I have left to spend is staring me in the face in two places, it's a lot easier to resist the 'pay for it next paycheck' rationalization!
Works really well for me.