I have official authority over this matter since my "rank" is now Uragaan (Just got over 600 posts).
Breaking the tail gives you a 10% chance for one. Cutting the tail and carving it gives you a 32% chance for one. Breaking the Jaw gives you another 10% chance to get one. Capturing gives you a 10% chance for one (x2 rewards, or the occasional x3 rewards). Carving the body gives you 8% chance to get one (x4 carves).
So it's best to break the tail and jaw, cut the tail, and kill it (Breaking the jaw isn't easy though, so you might be better off just leaving it be.)