Tim O'Brien speaks about Mandolin Warmup Exercises. What works on mandolin must work on bouzouki also. So have a look at it and decide for yourselves. By the way, some years ago Tim produced a DVD where he explains some of his techniques on Mandolin and Bouzouki. If you don't know it already have a look at it. I bought it some time ago and I think it's great.
Introduction to his DVD