It's really beautiful stripes on a wall, it's completely different from a blank wall or covered with wallpaper.
To have successful stripes like a professional, the painters tape should be carefully fixed with a level, and there should be no drips!
By doing several tests to understand why her first stripe had drips, she realized that her painting technique wasn't good.
As many have already done, she had brushed up and down, all along the painters tape and a some paint penetrated under the tape.
The technique with no dripping paint: Paint horizontally, from the tape towards the inside of the surface. In this way, there is no dripping paint!
By removing the painters tape, your paint stripe will be perfect!