Meet people beforehand to get a feel for reliability, interests etc.
Have rules about confirming attendance, such as deadlines. Attendance is patchy often. Have some contingency measures.
At the party, have clear rigid rules that each person accepts in person too. You can have a small fee, at cost and not above - showing what they are - and ask guests to bring drinks etc. Ideally have someone supervising who is not playing - you could pay someone. I get buff guys for example, as near naked butlers.
Until you know people, you don't know their reliability. Likewise, until you have parties behind you, you don't get a grasp on attendance patterns.
Have very specific attendance times. If it's a long duration, without a fixed time to arrive, people will feel they could turn up when they fancy it, such as when it's well underway. If they all did this, you may almost never start. Similarly, some people may want to come and go - those leaving aren't reliable to return, so think of how you can organise the start, duration and rules to create the party you want. Nothing will suit everyone but if you're upfront, they can pick you if it's right for them. Clubs are also places to get to know people who have a higher reliability than those unknown.
Plan some games. Have changing facilities. Consider neighbours, including for parking and noise. Consider guest restrictions, including verification levels, gender and singles/couples mix. Ask what people would like too |