I have a confession to make. I am the worlds worst painter. Honestly, my wife will not let me touch a paint brush unless it is to bring it to her. This is a great article about painting trim, which is in my opinion the worst part about painting any room. The bottom line appears to be take your time, cut in and do your prep, but we recommend you read the full article here
We also found a great video From Ron Hazelton:
