I agree with Alan, especially when he says that with a little practice, you will be surprised at how well you can do. I also agree that you should get the best brush that you can find, but maybe you could handle a 2 or 2 1/2 inch brush more easily. I use a 2 1/2 inch for most of my trimming up.
If you do use the masking tape, be sure to pull it off soon after you have finished painting. That is, don't let the paint dry.