I've been playing the piano long enough now that I thought it might be helpful to learn a few exercises for improving dexterity and/or "warming up" when one first sits down at the piano. My level is what might be classified as "upper beginner". (I have completed the first three grades set out in the classic John Thompson books as well as a few pieces on the side. My technique is pretty solid for the most part, I've been told.)

Currently I am only familiar with one Hanon exercise, which I was taught, but a (small) range of fairly basic ones, I think would be helpful. Hanon and Czerny are, from what I've heard, the two classics when it comes to piano exercises. Could anyone recommend any specific exercises that would benefit my playing at my current level?