I play supports, AP carries, and AD carries.
I have had the pleasure of jungling with Olaf more than thrice, and it usually works out, but that's my only jungler.
I don't really understand the point of jungling. I find that demolishing creep waves gives me much more money and exp than killing neutral mobs.
Here's the thing: there is only a limited amount of gold and exp income on the map, determined only be the amount of spawning monsters, with champion kills as a bonus.
If you have a jungler, you utilize all gold income one the map (toplane, bottomlane, midlane, jungle), your top and jungler will level faster (instead of sharing one exp resource together they both get their own). And a major benefit is to have one player that can appear anywhere, anytime, from the perspective from the enemy. They have to play careful because any 1v1 can turn into a 2v1 because they have no idea where the jungler is.
The above argument also goes for supports. Generally the ranged AD carry wants shitloads of gold, so he doesn't want to share his creeps with a lane partner. That's why you have the support, someone to help the AD carry into getting farmed and making sure he's safe (by placing wards, healing him (soraka), pulling enemies in for a kill (blitzcrank), shoving enemies away (alistar), etc).
I'm so bad at jungling. Then again, I'm not even level 20 yet.
It's been weeks since I last played. I want to like this game, but it's so difficult to get hooked into.
Save up all your IP and when you turn level 20 buy tier 3 runes like this:
Flat Attack Damage, Flat Armour, Magic Resist/Level
This will give you a good runeset that works across many champions and something to make jungling a LOT easier. No really, you need
runes for jungling. P.S.: don't bother with tier 2 and tier 1 runes, go straight for the good stuff.