I like to do some very basic in hand exercises then I tend to just let the reins lie on the horse's neck and see if they are interested in working at liberty. It's often not quite as tidy (especially at my level lol) but I have found it lovely to engage with the more spontaneous offer that horses can give in that situation. I often use raised or alternate end raised poles, turn on the forehand, turn on the forehand, perfectly square halts and lots and lots of transitions. Shoulder in and leg yielding can also be really interesting to try in hand as it is easier, I find, to see subtle errors on my part. My only 'tip' (love that I might even have one to suggest!!) is to have a good schooling whip so you can be really clear about what exactly you are asking for as I find I can be a bit 'muddled' and don't like to have to use a strong contact in hand (or under saddle actually) . If I am using a cavesson, then a schooling whip is even more handy tbh but you probably have all this sorted tbh!! Just hope that anyone playing with this might find it helpful somehow.
Oops I saw this a wee bit late!
What are you looking to achieve? Are you after groundwork horsemanship type exercises, classical in hand or polework type stuff?
There are so many things you can do on the ground that it's good to have an aim and something to work towards same as riding