Here is my Shen build guide. It does me very and makes Shen a great team mate all time around.

For runes I use health marks, seals, and quintessences. This is just one of many rune builds out there. You would easily get armor seals or something like that.

Obviously hes a tank so 0-21-9 will work fine. If you wanted him to do a bit more damage, then you could go 9-21-0. Either one works.

(Passive) Ki Strike-Every few seconds, Shen's next basic attack will deal bonus magic damage.

(Q) Vorpal Blade-Its a single target damage dealing spell that will heal any ally champion who attacks the target. Building a lot of health helps with this it useful because it scales off health. You can use this to regain your or an ally's health. I max this first for its Shen's only source of real damage.

(W) Feint-Shen creates a damage blocking shield around him. The shield has a low amount of damage block but increases as its leveled up. I level this second for the damage shield.

(E) Shadow Taunt-This is a very good taunt because it can it hit multiple enemies. The more champions hit by shadow taunt the more energy he will regain. This is leveled up last because you only need one point early.

(R) Stand United-This is what makes Shen one of the most annoying champions if your on the other team. Its a global ultimate that creates a massive shield on a target. He will channel then get teleported to the target if they are still alive.

Since his passive and Vorpal Blade stack of health, I like to build Shen with a lot of health. The build i showed you is a health build but it differs according to each team composition. Some other good items could include:
-Thornmail

-Guardian Angle

-Force of Nature

Boots:
I like to use the Ionic Boots of Lucidity because of the cool down reduction for his ult. Other boots that could work are:

-Mercury Treads

-Ninja Tabi

-Boots of Swiftness

The summoner spells I use are teleport and flash. Teleport is good for getting to the team fights because the tank always needs to be at the fights. You also could use it to cover a lane thats getting pushed and needs help. Flash is good for escaping, getting in position to use your taunt and just getting into position.

Different summoner spells:

Clairvoyance: Um...no your not a support

Exuast: Can be useful bot not recommended
Garrison: Dominion only...

Ignite: You don't want kills

Revive: If your bored

Teleport: Very good for getting to the team fights
Clarity: If you used this, you would lose

Flash: Yes this is very good

Ghost: This is also very good

Promote: Just don't do it

Smite: If your jungling then yes, it not no/

Cleanse: It could work but I've never tried it

Heal: It works but not as good as some of the others

Surge: No

Over all the best summoner spells to use with Shen are-

Teleport

Ghost

Flash

Heal

Pros: 1-Has good sustain in lane
2-Global ultimate
3-Aoe taunt
4-Good ganking

Cons: 1-Not very fast movement speed even in late game
2-Shelid is small
3-Pretty easy to kill steal with his Vorpal Blade (q)

Shen is a viable jungler but I don't play him as a jungler. He is one of the slowest junglers in the game.

If your lanning with a carry of some sort, you generally want to let them get the last hits. You can take a few but just not to many.

You want to be at the team fight. Taunting all of them will help your team do a lot of damage to them with out your carrys taking damage. You want to make sure your carrys don't die but this might mean you dieing. Its all for a good cause. If you can figure out who on their team is being targeted, you would try to use vorpal blade on them. This might let your carries regain some health. You dieing is not the end of the world since your are the tank on your team.

Some tips are:
1-Use vorpal blade to let your lanning partner regain some health. Throw it on the cannon minion so they will get the most health back.

2-Taunting the whole enemy team will give you a lot of energy back so you could use your shield.

This is my first League of Legends guide so give me any feedback you might have!