How much longer can we put this off? Painting a house is a major undertaking as well as an expensive one. Painting estimates will be a price for the total job, or can be priced by the hour plus supplies. (See my comment below about painting supplies.) Which way is best is up to you and I would base it on how much I trust the painter to be honest with his hours. An advantage to a one complete price is that you know up front what you are spending. I have done it both ways and when I use the hourly method, I have an estimate of hours put into the contract. You can also ask if you can buy the paint because I found that a paint store may give you the "painter's" discount or better, since you are buying a large quantity of paint. (Remember, the painter may get a discount but he may not pass it on to you.) Or, get the prices on your own and have the painter agree to a price per gallon. How neat a painter is also matters. You don't want to clean up after them each day. Try looking into their van to see how neatly they keep it.
How to find a painter: Definitely ask friends and neighbors for recommendations, although a local company whose vans/trucks you see all the time can't be bad - as long as they are legitimate. Once, on a whim, I asked a painter for his card when I parked next to him in the parking lot of a local store. Turned out to be the nicest man, lived locally and that was that. Your local hardware store (if any are still left in your neighborhood,) is also a good place to start asking for names.
And remember, this painter will be around the house each and every day. Make sure your dogs don't steal his lunch!