After a few emails back and forth, I will email them my manual to look over, as there's key points in there.
IF they are still interested after reading through, I invite them over for an interview. DURING the interview, I ask if they have any questions when they read my manual, and if (especially if they don't), I go through it page by page - to ween them out even more!

IF I'm interested in having them in my care, I will email them back to pay for the space, and come over to sign the papers/manual/contract.