I few months ago I learned how to paint edges freehand instead of taping them off and it has made a HUGE difference! I think it is also called "cutting in" the paint? I don't really know what the technical term is - I just know that I will never use painter's tape again!
What you do is put a tiny bit of paint on your brush and touch just the edge of the bristles along your trim. I like to run my brush along the wall about an inch below the trim first just to get any excess paint off. Then my brush is just barely wet and I carefully run the brush just a hair below the trim and go over it a couple of times, slowly working my way up to the trim until it is just right.
When I need more paint, instead of dipping the brush in the bucket, I run it through the paint that I had already put a little bit lower on the wall. Does that make any sense? It would also work to get a little painter's palette and put a little bit of paint on it to dip your brush in. However you do it, the main point is to make sure that your brush has just the tiniest bit of paint on it.
It also helps to get the bristles going in one direction and keep them that way. That is another reason that I run the brush lower on the wall before going to the trim. It gets all of the bristles going the same direction so that they don't pop out of place when I am trying to get a perfect line.
Another thing that is important when doing this is to get a high-quality angled brush. I really like the Shortcut by Wooster. It is about $5 but it is soooo worth it. The handle is made of rubber so it fits comfortably and bends with your hand which is nice for detail work like this.
Freehand painting takes a little practice but the results are so much nicer. Here is some trim that I painted using painter's tape:
Not only were there blotches from paint bleeding underneath the tape (yes, I know there are tricks to keep this from happening) but it was also impossible to get the tape lined up exactly to the line that had previously been painted. You can see in the left side of this picture where there is a tiny stripe of the old tan paint.
Now, using this painting trick, I have a nice clean paint line:
It takes a little bit more time to paint this way but when you consider how much time it takes to put up the painter's tape, this actually ends up being faster. Especially once you get the hang of it, it hardly takes any time at all.
The other thing I LOVE about this technique is that you get to see the finished results right away instead of waiting for the paint to dry so that you can take down the tape!