For funds you can specify how you want to receive the funds. The safest is a bank check or money order but that hurdle will probably limit who’s willing to do business with you. You can also choose to accept things like PayPal/Venmo/Zelle/etc. but that can open you up to chargebacks depending. There’s a certain degree of trust on both sides involved in these kinds of deals. You’ll need to create an account with whatever payment processing system you decide to accept.
For a contract I’m betting you can find some templates on these forums using the search feature, or you can try google. Someone else will likely respond to this thread with a link to a template.
