Horses and spurs?

ok me and my instructer have decided its best to use spurs on my horse for a better response on her part. ok i am starting back lessons (took a break for a bit) and i find my leg position loose in jumping. what should i do? i mean i ride as much as possible but any excercises that i can do at home that will benifit to this loose leg? and spurs? ok i use them and i see that my horse is getting frustrated and i think that it is because of my doing. i am not real sure how to use them. i mean i know the basics do not keep pressure on the horse and all but i find myself balling up in the saddle (like i scrunch up aand kinda hunch my shoulders during the canter and sitting tro i do not know why i find it hard for me to sit low deep and just relax. and another thing about spurs. i always tend to keep pressure on the horse by mistake and find myself galloping away after jumps..... ? help plz. thanks in advance!