First of all you need to know how much money you earn, for some people this is easy you look at your Wθ form and there it is, but for seasonal workers, small business people, it gets a little more complicated than that. If you receive income from a lot of different sources for a realistic value of what you actually earn itemize them, put them down on paper. Include all income, now is not the time to be hide money from the IRS you are just fooling yourself, you need to have factual figures here of your true income otherwise you will actually think you're in good financial shape because you know you got this extra income somewhere, but that's not always true.
If you do find a budgeting worksheet that you like, you can simply add categories to it or replace the ones you won't use with your own items. For example, many of these worksheets that you will find online have a place for investment income but if you don't have any investments to track either ignore that category or replace it with one of your own. _Once you view a few of these templates, you may realize that you have more categories of spending than you thought. For example, when first creating a budget, many people forget all about gifts, subscriptions, and pet expenses but by working with one of the preprinted templates, you may remember additional expenses you need to consider.