Millennial money expert Stefanie O'Connell says that if you are just starting out and trying to figure out how to budget, there is an easy way to learn without driving yourself crazy. She calls it the "cash envelope budgeting implementation tactic." You take physical cash and put it in an envelope that is earmarked for groceries or rent. That way you can actually see how much money you are spending in that one category. It forces you to confront your spending habits and learn how to save.
Once you have mastered budgeting this way, O'Connell suggests moving your money to a bank account where it can accrue interest. Cash is great, but when it sits in your wallet, it's not growing.