This is the way i see Sujuani, as a jungling tank coming from jungle to gank very often. And making sure team mates get kills with her slow.
I have chosen Resistance and ability power runes cause all her abilitys run on ap, and you need a lot of resistance as a tank.
9/21/0 is my setup cause she needs som magic penetration to deal dmg and still be a great tank.
I have chosen these items so that she can come in with alot of health and secure her team victory bye granting them speed bonuses and slowing enemy units.
I think she needs smite to do any jungle at all. And the reason i chose flash is that it is quite effective when trying to gank or trying to get away.
Pros / Cons
I would say the cons of this build is that she only deals alot of dmg in the start of the build, while only being tank late game.
Some cons are that you can easily gank when you get moveent speed and you have a great chance to catch someone far away.
Creeping / Jungling
With Sejuani i would recomend taking blue buff first to not waste so many health pots ask mid to pull for you. after that just keep farming till lvl 3. If you see anyone in the field is pushing go and try to gank that player.
I have chosen Northern winds first because it is the best ability at first while jungling. As lvl 2 i pick Artic assault because the knockback can mean the difference between life and death. Also is good for getting places faster. I chose to lvl up my permafrost first cause it is in my opinion the 2nd most powerfull ability she has (most powerfull is ultimate).
It's a good thing that you mark or tell you're team mates when you're ganking so that you dont stand alone against 2 players. By the way try not to ks and don't get mad if people ks you.