I agree with bitting up - I do this on Scooby when he wants to be fussy. It is much easier to bit him up, loose at first, and then lunge him and let him fight himself. I listen to my ipod and let him figure it out. Then when he softens, I tighten it up and let him figure out where his head needs to be to get a release from pressure.
Scooby also gets hot with a lot of barrel drills. I spent this week just walk/whoa and jog/whoa, serpentines and circles. I kept my reins loose and we ride in a snaffle, and if he didn't listen to a verbal whoa and seat cue then I followed with the reins and backed a few steps then repeated. We also do trail rides as well - lots of good advice from everybody about letting her relax under saddle by staying away from the speed and pressure. I go to a barrel clinic every Monday, and some of the horses there are nut jobs - too much speed, too much pressure, they just bolt away from it... rearing, jumping, running out of the bridle - all signs of too much speed work.