A Handshake is nice, but it is not enough
The best free piece of legal advice is to have a written contract. It does not have to be long, it should not be in legalese, and it should anticipate foreseen events that may change the terms of the deal. Memories fade, misunderstandings occur and if you have a written contract, you have a document that you can rely on to keep things on track. If you have nothing in writing and there is a misunderstanding as to the terms of the contract, you will have to file a lawsuit and have a judge decide who it right and who is wrong. This is costly and can be avoided if you just put it in writing.