Get some barrels or cones and set up a Figure 8 pattern.....and also a Weave pattern....and get to where you can do that without touching your reins. Do Clover Leaf patterns (each direction), BullsEye patterns (where the circle starts out wide but spirals slowly inward)....work nice and easy with going sideways on the ground, accept one step and reward her A LOT. Can you push her hind end and front end away on the ground with your hand? If you can, simply transfer that into the saddle, but with your leg.
As far as puzzles, one thing I've stared playing around with my horse is asking him to go over a pole (and eventually a jump) with a tarp laying underneath...to kind of make the obstacle more interesting and challenging. So get her used to TONS of things....umbrellas, plastic bags, tarps, cap-guns, whip cracking sounds, rain coats, etc...have her stand on something, and if you really want a challenge, ask her to put ONE foot on something....there's so much to do! lol.