Personally, I think your only options for summoner spell with Jarvan are Flash and Smite,  you can trade Flash for Exhaust if you like having even stronger ganks, but less mobility.

-If your jungling you need smite, it makes your clear times faster, helps you secure/steal buffs, dragon, baron. 

-A very powerful mobily spell, gives you another gap closer, another way to get out of your ult, allows you do have a stupid momments from time to time and survive it! Has a use it offense- flash to the enemy carry for your combo and defense- do flash over a wall and get away. 

-A strong CC and debuff, helps your ganks become even more potent, makes you very strong in 1v1's and let's you shut down enemy carries late game.

My runes for Jarvan, in season 2 they used to give both +10AD and +10 Armor pen with this page. Still good tho, gives you everything you need- killing power in the jungle and vs other champions, armor for safer jungling and Mr for fighting  casters  late game.

*Started using Full AD reds and Quints since they nerfed the ad/armorpen mix page

*A mix of AD and AS reds work well to now- since the extra true damage from machete is really strong

For masteries I go 9/21/0 getting some CDR, AD and Armor-pen in offense, then putting 21 points in defense and becoming a shield for my team, getting masteries that help my tank champions as well as jungle monsters.

I you feel like being a even more macho tank with more utility and less dmg you can go 0/21/9- getting things like:  Cdr, move speed and longer buff duration.

Grab E first, it's your main jungling tool- AoE Dmg and a passive AS and Armor bonus, take Q at lvl2 for more AoE and an armor shred. Take a point in w when you wish to gank (lvl3 or 4). Max Q then E take a point in W early and put more points in to it if you feel the need for a stronger slow/shield. Of couse take your ult at lvl 6,11 and 16.

*Some tips for every skill

Passive-Your passive is a nice boost in damage, if you can, try to hit as many different targets with it as possible.

Q-Use it mostly with your E, but you can also poke with it and wave clear (Q then E works best)

W-It's a nice AoE slow, don't forget you can use it over walls(like Phreak did in the spotlight) and also remember that it's a decent shield that might just save you from things like that evil  Ult.

E-Aside from being part of your signature move you can also you this skill to scout out the enemy team.

R-You can use this to stop your foes and then just Combo out of it, leaving them trapped.

*E used to be the skill to max first but this season it's all about the damage early

Jarvan is a champion that has a lot of options, when it comes to his build-he can go full tank, pure damage or tanky-dps bruiser. So there are a lot of good items for him.

-Helps you and your support ward up the map, Vision is Power.

-Gives you many stats, lets you do Tons of Damage.

-If you think the best defense is offense even the IE can work..

-Gives you MR and a shield, helps you deal with mages like 

-A strong item that lets you counter AS reliant teams (jungle, top, ad carry) or just a AD carry that is getting out of control.

-A item that gives you a good and strong mix of tank stats +AURA.

-Offensive option with a good active 

     Remember your build should always change- always look at the enemy team, maybe the is an item that counters them all? Or maybe only one of them is doing well and you can just buy items vs him. Then look at your team- what does it need? More of a dmg dealer or a tank? 

   The only thing you should be certain is that your build will start with a Hunter Machete  and that in the end you will have boots as one of your six items. 

*Still need time to test out all the new items, so this part of the guide will change sooner or later.