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.
You might spend more on "wants" than you think. A threadbare minimum of warm clothing is a need. Anything beyond that, such as shopping for clothes at the mall rather than at a discount outlet, qualifies as a want. Yes, the rules are tricky, but if you think about it, they make sense.