According to the EPA, professional painters must check for lead -- especially if a home was built before 1978. Many DIY painters forget to test for lead paint. Testing kits are available in home improvement stores for less than $40. You can also hire a lead testing and removal professional to do this work quickly and efficiently on your behalf. Lead paint can be dangerous; it's far better to find it before you put time and effort into painting your home than after the fact.
I was a painting contractor for many years and never asked for a deposit upfront. A good contractor should have great credit with his suppliers and an even better contract if the deal should go south before the job is done. Get to know your customer and explain how each paint covers so they understand fully before you have to apply 3 or 4 coats. If you didn't bid your job right and the client has already signed the contract then that is on you not the client. Yes I haven had to eat the difference but the client was happy and a return customer for years so I made up for it.
Can't speak highly enough of the service we received from James and his team. I did my due diligence and met with 3 painters. If I'd have met with James first, I might have skipped the other meetings. He talked me out of some extra work that wouldn't have come out the way i'd envisioned and showed me a packet full of successful projects, happy clients that dated back to the 1970s.