ride your horse on the bit properly and make sure he swings through his body and "opens" his back ( it's more difficult than you think )
Riding Serpentines and everytime you cross the centerline you do a medium trot and then come back to normal trot and bend for the next serpentine
Step 3 small circles 8-10 m and when you exit the circle do 15 m medium trot then circle again in the other direction
All those steps increase the quality of the trot but it is necessary to ride your horse on the bit properly first which can be really difficult sometimes.
20 min "long and low" trotting before you Start would be really good.
Focus on your balance, then focus on your connection with your horse. If you are bouncy/off balance, your horse will be too. Also, USE LEG!;)
Hello. I would say do some extended, and collected trotting exercises to help your horse understand trot more