I started painting my bedroom with that edger thing, and I couldn't get it to work evenly. Plus, in one section, the edging dried before I could go back and do that part of the wall, so there's an obvious line that says "guess who used an edger here?". Luckily that part of the wall is in a corner and I don't have to look it too often.
I also painted my bedroom ceiling, and even with an extension pole, I wasn't very good at it, and there are obvious lines from the roller dried in places. Again, luckily the goofs aren't above my bed or anything, so I don't ever look at it. (when I bought my house, my bedroom was the first thing I painted, so my bedroom is where I made all the novice mistakes).
I am also adept at making a huge mess of myself while painting. I will back into walls and get huge splotches of paint on my butt, or step in a spill and then leave shoe prints on the carpet. Make sure you wear clothes that you don't mind ruining, and get some cloth drop clothes. The plastic ones are cheaper, but they don't absorb your spills, so it's a mess waiting to happen. Plus, you can always wash and reuse the cloth ones. Also, TAPE, and remove the tape before the paint dries. I didn't do that when I painted my bathroom, and the wall/ceiling edge is jagged in some places from where the paint got peeled off along with the tape. Don't use a lot of paint when doing your edging, otherwise it could leak down underneath the tape, which defeats the whole purpose.
I've painted most of my house over the last few months since I bought it, and you'll get better the more you do it. But remember, if you mess up, you can always paint over your mistakes. :)
