GnuCash makes it easy to keep track of your money and it creates reports that will make your accountant happy.
I don't own a credit card (by choice), so keeping a close eye on my finances is really important, but I think whether or not you have a credit card, it’s a good idea to track all of your financial transactions.
It’s really the only way you’ll know what’s coming in and what’s going out. This is a great habit to do even if you don’t have any problems keeping a positive balance – and I would say it's essential to do if you struggle with debt.
Luckily I have no debt but I've seen a number of people turn around their whole financial situations just by starting to keep a ledger of all of their transactions.