As soon as you get money, assign it a goal based on what matters to you, then stick to that plan instead of guessing.
Envelope budgeting is a simple approach to budgeting where your income is divided up into envelopes allocated to different expense categories. By using this approach, you will know exactly where your money is going and what it is used for.
Assign goals to recurring expenses, and break up infrequent expenses such as yearly bills into montly bills so you are prepared when it comes time to pay.
As opposed to other approaches, you plan ahead instead of looking backward at your statements.
When overspending in one category, reassign from another category.
When using rule #1, one of the goals should be to repay debt of building a buffer, so you can live off of money from previous paycheks and not the current one.