#1 check all equipment and health of horse to make sure things are not making this horse excited.
#2 learn to do proper ground work with this horse to gain respect and control on the ground that will transfer to the saddle.
#3 when you feel your horse tense up in saddle, do circles, serpentines, flexing and back up 3+ steps to regain this horses attention back onto you. If your horse tends to take off, learn PROPER one rein stop (don't recommend with shank bits)
#4 learn to control all parts of your horse = lessons or video help
#5 don't ignore bad habits, they grow into deadly habits!!
#6 reward good behavior/habits with release.
#7 keep calm and a relaxed seat and back. Very big deal!