Take lyrics, tab and/or sheet music for your song have it noterised and mail it to yourself regestered mail. Regestered mail must be sealed or they won't accept it. Now the noterised sheets along with the sealed envelope will protect you in any court. Just realize pretty much everywhere stands by what the music is transcribed/written in so in theory some on can change the key and still steal your stuff. I personally don't suffer paranoia in reguards to that, only thing that I create that someone would consider are lyrics cuz my music sucks and if someone famous stold and used my lyrics I really would'nt make a stink over it simply for the fact thier money would tie it up so long I'd be dead before I got anything but to know Matchbox 20 sucked so bad they had to steal my stuff would amuse me untill death :)