Hi,
This is the first guide I've uploaded so please vote accordingly. Tips for improving the guide would be greatly appreciated and don't just tell me how bad it is, tell me how to make it better.
Thanks

Pros
- Great Initiator
- Reasonable damage
- Great skill combo's
- Lots of variety for skills
Cons
- Mana regen items won't help much with mana
- If you miss with skills they don't have really short cooldown

Start with cloth armour and up to 5 health potions
Depending on how much gold you have get boots or madreds
Once you have both boots and madreds, build a wrigglers for some lifesteal and damage with bonus free wards.
Then get either mercs if the situation requires it or just berserkers unless you have another personal preference.
If the other team has more attack than ability power then get sunfire, if not then build a frozen mallet.
Banshees is good as it can be used in any situation.
Next, build an Atma's impaler as you get extra attack damage from your health so this is really useful.
If you get this far then build an infinity edge so you get some really good damage with your passive.
Finally sell the wrigglers lantern for a Last Whisper.

Greater mark of desolation as this with the quints give some good armor penetration.
Greater seal of resilience because it adds to your armour.
Greater glyph of shielding for any magic resistance you may need, you could get this or possibly health glyphs
Greater quintessence of desolation for even more armour penetration.

21|8|1
In the offense column you have the mastery for your exhaust and some crit chance.Then you have bonus attack speed which can stack with berserkers if you get it and some ability cd. Next you have more armour penetration and increased damage to minions. Then attack damage, crit damage and bonus magic and attack damage to stack with your attacks and abilities.
The defense column you have magic resistance, armour and health regen.
Finally in the ultility column there is a point for ghost.

In total with this build you will have some good armour early game which will help you not die seeing as Jarvan's damage early game is good. Later game you will get some attack which stacks with masteries and runes adding up to a very good bruiser champion.
Thanks for veiing my guide and please give some advice in comments. :)