The last thing you want to do in a room is paint the wood trim- around the doors, the baseboards, and the crown molding if you have it. and it's exceptionally important to tape off the edges of this. And a lot times when you're using trim paint, especially if it's oil-based paint, it has a tendency to seep, even under the tape. No matter how well you tape and how well you press it against the edge. So I have a little trick to take care of that seepage. And that is to apply a very thing layer of caulk along the edge. It doesn't have to be much at all because you're basically going to wipe it off. Once you've done that, just use a wet finger- nothing beats a little spit- to take off the caulk. But you've still left a very fine membrane in place which is going to prevent the paint from seeping behind the tape.
And after that, it's really just very straight forward. Things like a door stop are a lot easier to just remove than to tape around. The thing you want to do with trim paint is just to put on a light coat and don't overwork it. There are flattening agents in the paint which are going to cause it to flatten out. A lot of times people will continue working the paint with the brush thinking, well, I need to get rid of these brush strokes. But all they're doing is thickening the paint the more you work it. So what you want to do is use just a couple of strokes to apply it, and then just leave it. It will flatten out, and you will end up with a really nice job.
To check out a free video
of how this is done, look at this one about Painting trim.