This will be a short, quick look guide. Im not going to talk about counter picks because i think that it really depends on your play and your knowledge about the enemy champion.

Pros:
1. You can build almost anything on him. Very versatile champion.
2. A lot of cc (a knock up, a trap and a slow)
3. Has some range, so he can deal with almost everyone, as opposing to most other bruisers
4. He make the adc and ap mid have nightmares of him
5. Very team fight oriented, with dem aoe ults
6. O, and he counter picks the all mighty olaf
Cons:
1. Will lose most of 1v1 with other bruisers like jax, riven, olaf...
2. Bad use of ult, or anything, can get you or someone in your team killed
3. Has no real sustain early on
4. His W is really weak

Jungle: I take ad red and quints because it gives me a good buff early and armor and mag resist is a must have.
Top: As already said-armor pen beast!

Jungle: I go for 9/21/0, well its a bruiser page so... yea.
Top: 21/9/0 I take crit and basically full damage, with health and sustain in defense.

Top: So, the sixth item is your choice. I would most of the time go for blade of the ruined king or hydra but its ok to adjust. Try force is really good, wits also. And executioners calling is kinda the last item choice of all these but it actually really good. Everything else is armor pen, with an addition of warmogs, just for the high sustain. If you are going jungle jarvan with this armor pen build i recommend getting the spirit of the elder lizard, but not before black clever and giants belt.

Ok, so sheen is somewhat a good item on jarvan. If you build it its obvious you're going for trinity, right? I don't. I go trinity only if im a head, like really ahead. If i buy sheen, i buy it for the buff, which is really good. However i just leave it until i finish everything else(which usually doesn't happen). Sometimes i go for iceborn gaunglet but very rarely. But is sheen worthy?
I think it is. But if you are behind don't buy it. That's my recommendation.

Simple. Start with e. Max q than e than w.
In jungle i start with E than take Q than W. After that i take a point in E and than take two points in Q, than max E, finish Q, and take W last.

Top: I usually take flash and ignite, but teleport can be good, also exhaust, ghost. but i prefer the first three. However, if you wanna try out crazy stuff go for revive and teleport.
Jungle: Smite is a must have. And again i go flash, but teleport is also good for tele ganks. Otherwise i dont see why take something else.

A lot of people will say that jarvan is underpowered. Even though his ult is bugy and he isnt op like jax, he is a fun champion and actually useful in team fight, just learn to play him. He is one of the most balance champions. So good luck with this great champion.

ALSO YOU CAN CHECK : http://www.youtube.com/watch?v=66amLUiRNJQ ITS A JUNGEOLOGY VIDEO OF JARVAN BY SAINTVICIOUS.

Still in progress, so try it, change some things, be creative, and good luck.