Any advise on improving my martial arts training?

Look into getting a stretching machine. They help a lot with flexibility. Try to stretch as much as you can. A very good way to strengthen your legs is swimming and squats. Get a good floating vest for your weight and get in the deep end of a pool that is at least 2 ft. deeper than your height and run while floating. We did this for track practice in the winter when it was cold and in the summer to cool off. It works unbelievably.