Try to always have your
smite ready when going for a gank, the extra movement speed and slow are a great asset. You should also try to work up your passive by switching in between stances when running up towards the enemy, before hitting them in the face with Bear Stance. Try to move along with them as you chase also, going forward after every auto. Before you do all that, though, make sure they're overextended and you've pinged to your laner that you're going in, they need to follow up.
EDIT: Not a ganking tip, but Udyr is a fantastic duelist and counter-jungler, don't be afraid to steal from the enemy jungler, show him who's boss! So long as you know your match-ups and play it right, you should be able to dominate Champions like
or
early on.
Hope I helped, best of luck to you.