This all comes down to the rules.....1. references....does the contractor have them??? I ALWAYS furnish all my prospective customers them....no excuses...2. insurance....again, I always furnish proof....3. Read the proposal carefully...I ALWAYS list materials down to tape used, the brand, the grit of sandpaper, the manufacturer, etc....its INEXCUSABLE to not list all of these items....I am a member of the PDCA, the Painting and Decorating Contractors of America, the foremost authority in the coatings industry and they also approve of what I listed....if you do not follow these guidelines, you will NOT get a job reflective of "professional". Look for the PDCA where any painting contractors are, if they are not a member, RUN!
We had a bad experience with an interior painter years ago, with the crux of the problem being him overcharging us at the end for "extra work" he didn't anticipate. One thing I'd strongly recommend is making sure it's in the contract that any additional work or growth work is estimated and communicated to the owner as soon as it is identified, otherwise the owner is not liable to pay it at the end.
These are some fantastic questions to ask and I particularly like the one that is concerned about safety for the painters. After all, if you have a large home and you’re hiring them to paint the exterior of that home then they’ll likely be on scaffolding. Because of that, you need to make sure that the contractor not only provides appropriate safety training, but has the correct liability insurance as well.
Even if you go it alone, specialize to keep your initial investment low. If you do only interior painting, for example, you might get by with one ladder, a few brushes, rollers, basic hand tools and such, for an investment of less than $300. Again, you can add to your tools as you need to (every job is a bit different), and parlay profits into the equipment necessary for exterior painting or working on large commercial properties.
Maybe you've just moved into a new home, and you haven't got around to buying brushes and rollers yet. Perhaps you're worried that your brush-skills aren't that good, and you won't achieve that professional-looking finish that you’re really going for. Handy professionals will turn up with everything they need to get the job done, from ladders and brushes, to rollers and tarps. You just have to provide the interior paint and primer!