List your expenses starting with the most important to the least important. Listing the expenses in order makes it easier to make cuts in your budget if needed. The most important should be things that cover your necessities. You will need to cover your housing, food, utilities (not including cable television), transportation costs, debt payments, and savings goals first. Then you will list luxury items which can include clothing, entertainment, eating out and gym memberships.
If you're self_employed, your after_tax income equals your gross income less your business expenses, such as the cost of your laptop or airfare to conferences, as well as the amount you set aside for taxes. You're responsible for remitting your own quarterly estimated tax payments to the government because you don't have an employer to take care of it for you.