Cooper & I had a wonderful lesson with Chris Hickey recently. Collection, especially as to how it relates to flying changes & pirouettes, was the focus of much of the lesson. It is easy to end up either a little stuck in place or a little flat and not quite round enough in the collected canter. We worked a lot on adjustability within the canter, maintaining the correct frame throughout.
Chris had a good exercise for the pirouettes: Develop a working pirouette, and enlarge it for a stride or two, then make it a little smaller for a stride or two. Then leg yield out of the pirouette. Repeat several times.
To get good tempis I need to get the horse collected, and jumping forward. Morten Thompsen once suggested I imagine a jumping scenario. What works for me is to recall from my Eventing days: a drop jump to a big vertical a couple of strides away.
An actual exercise that I have found useful for 2-tempis: When I get a really good pirouette (Cooper’s pirouettes have improved dramatically recently) then come out of the pirouette and ask for 2-tempis. Today we had five 2-tempis in a row, and I could have asked for more…they were balanced, jumping and straight. The ½ pirouette helped me get the right canter for the tempis. Now I need to work on getting the correct canter, which I need for the pirouette, and take it straight to the tempis, without letting it fall apart.