Below are some contract tips for commissioned artwork that have served me well for many years. After some bumps in the night, I have learned to adjust my contract accordingly, to avoid future scrapes, particularly around internet scams or exchanging funds without a contract.
Standard Art Commission Contract: (mine is concise at two pages long) Always include your contact information, signature logo or image of your work, an artist commission statement (1-2 sentences), client contact information and commission details.
Commission Details: An important paragraph outlining specifics of the actual commission. Include medium, canvas size, anticipated delivery date, actual delivery date space, space for a photo of finished painting, full price amount (including sales tax), deposit amount (non-refundable).
Artist Commission Statement: Note details from the conversation with your client, if the pooch is going to wear a requested blue collar, or the house commission must include the front hedges, or the beach must be painted at sunset.
Deposit: Require 50% down, non-refundable, paid in full, clearing your bank account, before you lay brush to canvas. On internet orders, where I don't get to meet the client, I ask for full payment upfront.
I prefer PayPal or check. No money orders.
Commission Presentation: Will you provide a sketch for approval? This usually takes place over email if the client is out of state. Will you show them your commission 'in process"? I say "no" to this one as it opens a whole can of worms from the fairytale forest floor.
Expect to have to make changes or don't do commissions.
Making Changes: Art commissions are team work including you, the client and perhaps an agent. Although I have not had a commission rejected in nearly 25 years of working with clients, I implemented a change policy after a painting came back years later for me to change the hands. I give a two-week grace period during which I will happily make reasonable changes completely free of charge. Beyond the grace period, I charge $150 an hour for revisions. This encourages clients to get back to you before the grace period is over.