My credit is shit, and only recently have even been ABLE to get approved for a credit card. I got it for 2 purposes. One is that since it's a 0% intro for 15 months, I had a $700 purchase that I wanted to make, but not the cash for, although I KNOW I will be able to have that paid off in a certain period of time (less than the 15 months) so yeah, just a short term interest free loan, so to speak. The second reason is to try to build some credit, in order to be able to buy a house in the future. I'm not one that thinks they should finance everything, but to be able to obtain a mortgage would be nice. The plan after it is all paid down is to play the pay it off every month game, not using it for more than we would spend otherwise.
The bank account is pretty thin right now, we are in the process of getting on track with our finances, after being together for almost 8 years, and having everything in a mess for that entire time. Our HUGE challenge right now is to reduce all of the SPENDING that we do, beyond bills and food, etc.
I have put together a really slick spreadsheet through Google Sheets that we use to track spending, and manage our income/expenses. It has a "bucket" that we put the money into that we need for the planned monthly expenses and weekly expenses, that separates all of that stuff from the rest.