Caveat! Caveat! I am a serious pathalogical budgeter.

I'm super anal, so it works for me, but not everyone would want to do it this way ...

But when I first made our budget, I projected what all (and I mean all) likely costs would be for the next 12 months, and then broke it up over fortnights.
- included rent/mortgage, utilities & rates, phone, petrol, car rego, train ticket, insurance, uni (service & amenities fees, text books, printing credits), gym membership, internet, allowance for Christmas/wedding gifts etc, medical costs, etc...

I also projected anticipated-but-hopefully-unnecessary amounts.
- included services/car repairs, incidentals ...

And then I figured how much we could afford for everything else.
- included food, clothes, slush (pocket money), entertainment (and grog came out of this one ) ...

With an allowance for a certain percentage of savings.

And I must admit that I then have double entry books on excel, with journals for each financial year, then allocation pages for each fortnight, and separate spreadsheet pages for each category, so I can see how I'm going for the financial year, and I can alter my allocations periodically as things change ...

HTH