Painting Chair Rails

[BOBOYDDS]

I'm pretty new at all this, but i recently painted my walls and placed the chair rails around the room. I am now ready to paint the chair rails. I have a couple of questions.
I want to know the easiest way to fill in the gap between the rail and wall, also the easiest way to paint it.
I tried taping the wall and placing a paintable caulk in the gap before i painted, but when i took off the tape it still leaked a little and the fill between the wall and rail werent that clean.
Should i just caulk everything and paint the rails, then touch up the walls after?
Lastly, how do i avoid all the brush strokes i am getting on the rails when i paint them?
Thanks for your help!

[chfite]

With painted trim, the gap is caulked to the wall or adjacent trim, then painted. Tape is over-rated in my mind. Just get yourself a top quality trim brush and work on developing a steady hand. Lightly sand the primer coat and the first coat of paint to help provide a smooth surface for the last coat.

[Sawdustguy]

Giving examples of quality brushes. "Ox Hair or Horses Hair" Expect to spend between $25-30.00. Also, if you go to a quality paint store, I believe they sell an additive that will help eleviate any brush marks or tone it down so it's not so predominate.