Remember: when selecting your brushes, that the lower the size number the finer the lines to be produced. These brushes must always be oiled when stored and kept flat. I prefer to use neatsfoot oil which is a traditional pinstripers choice. Some books, written by professional stripers, tell you to trim the 'belly' out of the brush.
Don't do it ! It destroys the paint holding capacity if you go too far. NOT for beginner