House is a beige, trim is white, green metal roof and shutters. What color for the front door?

I was charged $12,500 for painting 1000 sq ft max of drywall and baseboard in an open rectangular basement with 9 ft ceilings in the original off white color. The painter was able to get an exact match. There was NO furniture or anything else in the way that had

Want to get someone to paint over my tin roof that is blue to a hunter green. People are saying it will peel or discolor, but would if it is prepped correctly? Thanks for the information.