A couple of years ago, in our old house, we noticed that our exterior window trim paint was flaking off and exposing bare wood. Not wanting to risk having to replace all the windows, we inquired about painting the house. Found a reputable painter who sent a fellow out with a paint color book. The house was part stucco and part siding. There were four colors to pick- primary color, primary color accent, secondary color, and secondary color accent. I agonized over the book for quite a while, but finally chose my four.
It didn't turn out great. I didn't pick a different enough accent color for the primary, so it looked kind of blah. We actually would have been better off taking the painter on a drive around our neighborhood to look for a house we liked, and then just saying, "OK, those colors. Match those."
Now, maybe that advice is better for people who really don't care that much, or don't have that much of an "eye." My wife and I are both of those!
We ended up selling the house less than a year later. The new owners re-painted it.