This Guide is based on the Tiger Stance, focusing on more Damage than tanky Items.
You are still a bit tanky while dealing more damage than the others in the team (except AD Carrys).

Well, here are some points
Pros:
-Very high Damage
-Fast as light
-Fits on nearly every team
-No Mana problems Lategame
-Can turn tables in fights
-WEARS FUR

Cons:
-Can only run to escape
-Must be in melee range to deal damage (easily kited)
-Manaproblems earlygame without blue
-[*] Turtle Stance got a nerf, not so strong anymore

The items listed above will give you enormous damage. You are still a bit tanky, tough you shouldn't try to engage.
With this build i have scores like 12/1 or 15/3. People will freak out "WTF dat damage" etc. but don't worry, it's awesome.
You might consider buying something else, changing Youmuu's Ghostblade to something like Force-of-Nature. You don't have to buy these items only because i say so. Try picking the best items, this is just a suggestion.

Due to [*] Tiger Stance you are allowed to deal very high damage already in the beginning.
Try to stack up your passive in jungle, so switch between Tiger and Turtle Stance at the right time to get the most attack speed out of it.

Udyr is very weak without blue in the beginning, because your [*] Turtle Stance won't help you that much with mana. Consider the following: Your Blue gets killed by the enemy team. What do?
I tell you! Go and get THEIR blue. Most of the time people counter jungle with the entire team, just run to their blue, and it's okay. You should let one minion at blue live, so their blue doesn't spawn.

Well, i hope you liked this guide. I made it a bit way too fast because this day i have no time, but i will work on it tomorrow, don't worry.
Be free to write any comments.