It's up to you. Outside is much harder because it requires more prep, patience, time, help, money and of course, effort. I have been painting my own houses and rental properties interiors for 20 years, and I painted the exterior of one, once. I then had it promptly done again by professionals who said it would have been cheaper if they didn't have to undo my work first. My advice is to get pros for the outside because everyone will see it.
The graph says the average cost to paint a home interior is $1600; at the high end, $4,000. But for what size home? I'm getting estimates for painting an 1800 square foot townhome in the range of about $6500 - which includes sanding and repainting all doors, and painting all trim, walls and ceilings. What does the range above include and for how big of a home? Thanks.