I know you mentioned payment already, but I wanted to reiterate that it's important to get payment immediately before you do anything further, ensuring a commitment from your renters (whether friend or stranger). Highly suggest a signed contract expounding YOUR terms (whether renter is friend or not).
Also suggest full price now (non-refundable), but other reasonable option is half now and other half 1-2 months prior to check-in, with first half-payment non-refundable. Stuff happens, and you don't want to be found lacking.
No one who is genuinely interested and trustworthy should be opposed to a contract, as it protects both parties. Good luck, we've always had good experiences renting (to and from).
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EDIT: thanks Denise, you're exactly right...... in hindsight, 1-2 months before check-in is indeed too long to wait. I was thinking of the one time I did do that---- one time due to extenuating circumstances of a friend, all others were full price up-front. I do insist on contracts though, as it does have the effect on the renting party that it mentally reminds them that it's "enforceable", and that is a good deterrent to defaulting, and prompts payment in a timely manner as specified in the contract by a definite date (usually a week or so away from initial verbal commitment). thx
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