Watch the Creating A Simple Practice Loop online guitar lesson by Robbie Calvo from Creative Looping Handbook

The best way to create a guide rhythm part is to play a "scratch" muted rhythm that has no pitch and only the rhythmic content. You can do this by playing the rhythmic feel you want across muted strings.

In this example, I chose to play a shuffle rhythm by playing percussive scratches that my chords go well over. This will definitely get you started in creating solidly timed loops.