Bob Spina taught me to finish off the ends as shown above.
1. Lay down a line of tape on the bottom to give you the sharp edge you want.
2. Bend your ending lines of tape (like the top photo)
3. Paint in your stripes (multi-color job shown)
4. Remove your tapes . . . and you get this neat, sharp finish of lines on your stripes. I like this method better than going back with a striping brush since it's faster and leaves a cleaner line.
5. You can get "professional results" and you don't have to be a professional with this method.