The trick to scrollwork is practice, practice, practice. Some use impression patterns and such but I just go at it freehand. I never am able to follow the lines of the impressions. When you first start scrolling try it with one color - cake and scroll. Your errors won't show nearly as much. Once you've done it a time or two switch you'll feel confident about switching up the colors. Scrolling really intimidated me until I'd done it a few times. Still working on my technique but I am getting better.
This online course with Joshua John Russell may be of interest to you: