Most couples start by asking for a single number. A more useful first step is deciding how the money should be split.
The three big lines
Venue, food and decor usually take the largest share. Food scales with guests, so your guest list is the most powerful budget tool you have.
Where to hold money back
Keep a reserve for the things nobody prices in: extra rooms, generator hire, overtime for crews, and last-minute guests.
A simple way to begin
Fix the guest count, pick the season, then get three venue quotes on the same date. Everything else follows from those.