i know i am a girl, but i play defense in lacrosse.
on of the biggest things that our coach emphasizes is footwork. we do a lot of agility drills to keep our feet moving and a lot of man down drills.
also, not sure if it is as important in guys lacrosse, but talk. talking on the field makes any defense better because then everyone knows what is going on where.
call for help early. its better to call for help and not need it than to get smoked.
thats gonna make a solid d.
one thing our goalie does is yell out where the ball is so if someone face gaurds for a sec then they always know where the ball is. it helps so much.
you sound like you are gonna make a good coach. i coached youth lacrosse and reading books helped a lot. they supply good plays and drills. also, uslacrosse.com has a coaches section thats pretty legit.