Consider downloading some kind of checkbook ledger app. Anytime you get paid, re-balance it and make sure it's correct. Then, use it for EVERY purchase that isn't cash. Once you get into the habit of not needing to re-balance it, switch 100% of your purchases to credit card, and keep the habit up. When it comes time to pay your credit card bill, you will have the cash you need to pay it off, and you will also be building credit which will give you more purchasing power down the road.