I'm a big fan of using transitions in riding. Those, plus figures such as circles, serpentines, spiral in/out and basic lateral work, are really a foundation for me in every thing I do. I find them particularly helpful in working with a horse that knows how to soften through the jaw, neck and back and engage the core, but may have trouble maintaining softness consistently. But the trick for me is that I have to ride the transitions in a way that promotes and doesn't inhibit the softness, and for me that means riding transitions with my breathing, feeling the rhythm of the new gait in my mind and body, keeping my eyes up and staying relaxed, rather than using either my hands or legs to cue (some horses may need a leg cue but I find if you can feel the rhythm in your body, and your horse has learned to read that, leg is rarely needed for upwards transitions). I try to keep my contact as consistent and soft as possible (or even ride on a loose rein), and my legs relaxed so as not to block the motion. And I think of all transitions, even to halt, as forward motions - it's all forward - so I try to keep the motion flowing and uphill - for me, the most important element in achieving that is not to block with my hands or by holding tension in my body or legs.
Dawn and I had a really nice work session today - it was our 15th ride at the new barn. We had the entire indoor to ourselves (unusual at that time of day), and after lungeing briefly - she really didn't need to lunge as she told my by her relaxed trot and perfect (e.g. no leaps or hops) canter transitions, and her excellent responsiveness to my verbal commands. It was much warmer today than yesterday - about 60F which is pretty warm for this time of year. It was extremely windy though, and Dawn coped well with all the rattling and creaking the indoor arena was doing in the wind.
We did some very nice work at walk and trot, using cones and figures (cones are my friend), but she was working up a bit and starting to rush a bit at the trot, so we moved to doing lots of transitions. We did lots and lots of walk/trot/walk work, and threw in some halts, some backing and some halt/trot work as well. One thing I love about riding Dawn is that when she and I are in sync, she's incredibly sensitive to everything I do or think, and therefore incredibly responsive. She's also great for me in that I have to pay attention every single second - there's no time off when you're riding Dawn. We did whole series of 3 strides at trot, 3 at walk, 3 of trot, and then different numbers of steps, with the only cue I gave her being my thinking the new rhythm (1-2, 1-2 then 1-2-3-4 for trot/walk and the reverse for walk/trot), breathing out on the transition and also slightly relaxing my back for the downwards transitions. It was magical - she was right on it and transitioned the second I changed the rhythm in my mind. And since I wasn't using my reins to cue, her contact and softness were maintained through the transitions and the transitions stayed uphill.
I was delighted with her and told her so - she's an incredible mare and I'm fortunate to have her to ride at this point in my horse life.