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.
Finally, do it again. After you have completed your first month of budgeting, it will be easier to plan for the next month. At the end of the month look at how you spent and make adjustments for categories in which you spent more than you planned, and cut back on the categories that had additional funds in them.