I dunno what stores you have up there, but Office Depot around here has "EZ Contract" kits for whatever you might need. Honestly though, it's not worth the money you'll spend on 'em. Put something in writing, deal strictly with cash (if that's not possible, demand payment up front, or half up front, the other half when the job is done).
It's just the price of doing business. My contracts state that any nails, screws, or adhesives remain my property and are strictly on loan until payment in full is rendered, I am to be given a house key for access to the house, and the time frame for access granted to me to enter the house is usually given as one month longer than I think I'll need to finish the job. If I'm ever hosed on payment (never have been for THOSE types of jobs), it's explained when they (ALWAYS happens) ask me about that clause in the contract. It's simple. If you don't pay me, I'll be back to pick up my screws, nails, and adhesives.
I also don't pay for materials. That's the other person's responsibility, and the determining factor on when work starts. I give them a list, and will not start until everything on that list is there for me. For your work, I'd figure out some way to image your work and transfer it over only after completion and/or payment for services rendered.