Someone's coming to try croquet. They've signed up, they've got a date. The club's job is to make sure they enjoy it.
If they enjoy it, they come back. If they come back, they join.
Someone meets them when they arrive and shows them round. A few basics, before play. Morning Tea or drinks in there too. Before they leave, they get a flyer with the club's two fixed session times and what to expect next.
No hours of drills or a rule book. Show them how enjoyable croquet is.
From week two, they turn up to a regular session and play alongside members. Same time, same place. Easy to organise.
Over a few visits, they see what the club is about. When they're clearly enjoying it and keep returning, it leads to membership.
The game does the work. The club just needs to not get in the way.

Getting people through the gate costs money. Ads, flyers, time. If the welcome is bad, that money is wasted.
The Come & Try Guide writes down what good clubs already do, so it doesn't depend on who's rostered on.
The complete process, including how to run sessions, what to say, and common situations:
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Clubs need new members. Advertising costs money. When someone walks in, the club has already spent to get them there. A good first day turns that spend into a membership. A bad one writes it off.