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.
An average wedding will spend 50% of their budget on the reception. This includes food, drinks, and venue. 10% of the budget is spent on the attire. This includes bridesmaid dresses, suites for the groomsmen, as well as the bridal gown. Another 10% is spent on the decorations, and another 10% on music. Plan to spend another 10% on a photographer or a videographer, and the rest for miscellaneous charges. This of course is not set in stone. Your wedding might be much different then this. But when setting up your wedding budget worksheet this is a good place to start.