Before you book anything, write the one line

Most events that underfill were doomed at the idea stage, not at the invite stage. The founder booked a room, picked a date, and then tried to work out what the evening was for. By the time the invitation went out there was nothing in it a busy person could repeat to a colleague.

So write the line first. One sentence, in plain words, that a guest could say to someone else:

"It's a dinner for heads of finance who've just moved onto a new billing stack, and everyone there has already done the migration."

That line does three jobs at once. It says who belongs in the room, it says what they get, and it gives the guest a reason to bring the right person with them.

Test it before you spend anything

Send the line to five people who'd be perfect guests. Don't invite them yet, just ask "would you go to this?" You are looking for one of two answers:

• "Yes, and can I bring X", you have an event. The topic is sharp enough that they can see who else needs it.
• "Sounds interesting", you don't. That is the polite version of no, and it will convert at about the same rate on the night.

Five messages costs you twenty minutes. A half-empty room costs you the venue, the catering, and the credibility of the next invitation you send.

What the line must not do

It must not describe your product. The moment the sentence contains what you sell, it stops being something a guest repeats and starts being something they forward to procurement. The product shows up in the room as context, the reason you're the one convening it, not as the agenda.

It must not be a theme. "The future of payments" is a theme. "Six finance leads comparing what actually broke during their billing migration" is an event. Themes attract people who are browsing. Specifics attract people who have the problem.

The line is also your filter

Once written, use it on every decision. Does the venue fit the line? Does this guest fit the line? Does this agenda item fit the line? Anything that doesn't, cut. A tight event that does one thing well gets talked about. A broad one gets attended once.