Begin by listing your income for the month. This should include any paychecks you receive, as well as income from other sources like child support or investments. If you have a business, you should include the amount that you pay yourself out of the business each month.
Lastly, if the numbers still aren’t adding up, you can look at adjusting your fixed expenses. Doing so will be much more difficult and require greater discipline, but on close inspection a "need" may just be a “hard to part with.” Such decisions come with big trade_offs, so make sure you carefully weigh your options. Tip: Small savings can add up to a lot of money, so don’t overlook the little stuff. You might be surprised at how much extra money you accumulate by making one minor adjustment at a time.