both.

cuz practicing the wrong stuff can be disastrous.

xMika - such as? for instance if your a drummer, and u see ppl holding the traditional grip and u go, wow! cool! i wanna do that too! and u keep practicing the trad grip just like u saw, but the thing about the traditional grip is about how ur finger fulcrum react in giving the stick the rebound it needed. and if u just mimic the looks of it without getting fully understand how the stick supposed to move, ur sound wud be totally off the hook, not to mention getting urself injured in the process.

seriously anything u practice in the wrong way can be dangerous, if u ady biasa using the wrong technique in ur playing, it wud be hard for u to change it. so thats y we need instructor to teach us and guide us throughout our playing, so that u can ask him and he can observe u on whether ur doing it right or wrong.

make sure u dont practice the wrong stuff though