I always show the clusters (as mentioned earlier) in this AND arpeggios; if you show how the hand should look based on where the thumb is, you should have two 123 clusters, and two 1234 clusters.
I also make little rhythmic songs to show the emphasis. In this case (imagine each note is an eighth value, and after seven notes, there's an 8th rest to make two complete groups of eight)
ONE two three ONE two three four (rest) ONE two three ONE two three four (rest). If you say that quickly, emphasizing the ONE, it makes a pretty catchy beat.
I'll do a mix of those and clusters.
Also, make sure that the student isn't just saying "ya ok, that makes sense" then goes home for a week practicing with the wrong fingering, forgetting everything you said during the lesson/wrote in the notebook. I've had a girl do that so many weeks in a row, that I actually wrote in her notebook "check off here if you read the note book this week", and sure enough no check mark. She's the kind of student who will totally forget any method you bring to the lesson, stumble through scales/pieces/whatever ONCE a day and consider that ample practicing.