After abandoning midlane for good with the most recent Eve nerf, I have become a true disciple of the One True Build: Warmogs, 1 damage item (BC), stack giants belts forever. I have switched to only playing champs that can use this build to great effectiveness, dishing out piles of damage with only 1 offensive item and stacking health to mitigate the pen changes. The roster: Olaf, Darius, Lee. It's strong, and it's carry, but you can't always effectively tank because you can't make them hit you. After making an arbitrary decision on which of the 6 remaning champs I had to buy, I may have stumbled into something wonderful. Ladies and Gentlemen, disciples of the Church of the One True Build, I give you:
Jungle Tank Hecarim
9/21/0 Picking up Armor Pen in O and Bladed Armor / initiation stuff in D.
ArPen Reds, Armor yellow, MR Blue, MS Quint
R>Q>W>E, Start QWEQ
Machete+5, Stone+boots. Sheen, Giants Belt. Boots of choice, Warmogs. Giants Belt. Elder Stone if you didn't buy Merc, Sunfire if you did. Giants Belt. Do you see the pattern?
We are slightly altering the One True Build, your one offensive item is a Frozen Fist instead of a BC. Sheen procs like crazy on Hec and it helps you with mana early. You may never finish the fist, you may never finish the jungle stone. This is fine, this is good. Stack those belts. The entire principle behind this build is to get as much health as possible, as is it your most valuable asset in teamfights. Your effective health skyrockets in teamfights with your W active.
Hecarim is generally (and perhaps meant to be) played as a "carry jungler", I've seen it done as 9-0-21 and 0-9-21, building damage items in lieu of survivability. It's awesome, it's fun, it's SPEEDPONY! We are not doing that. Solo queue is for the One True Build so you can survive the onslaught of a coordinated teamfight and clean them up.
Your goal in any fight is to get behind your target and E him away from safety (escape routes, his tower, his teammates, whatever). E is sort of a trap ability because it increases your movement speed as you charge, and then knocks the target away from you. You need to loop around behind him or use the speed boost to get behind him, then turn and connect with the E's active to direct the target. If you simply rush in and attack, you will become a victim of Bad Alistar Syndrome (tm) where you are constantly saving your target's life. A common tactic is to position behind a tower, then E in and butt them out from under the tower into the arms of your waiting teammate. For teamfights, you can use your E speedboost to initiate by running through the other team, then turning around and using R back through their team towards your own. Very effective initiation as they will either scatter to get out of your way (setting someone up to be picked off) or try to focus you (bad luck for them as you will R through them and they will get crushed in the fight).
And now, a word on jungling. I am not a good jungler, I am playing in the placement level, games are chaotic. You have 2 choices as a jungler: farm or gank. If your lanes are pushed then the optimal thing you can do is farm both jungles. If your lanes are not pushed or their jungler is camping one,
*GET YOUR ASS OUT THERE AND GANK*
Playing at low elo, a good trick to use is go botlane and stay there, making the lane an effective 3v2. When their jungler shows up to respond, pull the same trick toplane. If you force their jungler to respond to your presence, he will not be able to get anything done. Keep track of the timers so you don't leave the big creeps up, drop your own important wards if you have to. Most people's map awareness is so bad that by the time their jungler shows up in response to your lane pressure, you will be on the way somewhere else. HE WILL NEVER CATCH YOU. Think of yourself as a funny little arsonist running around setting fires that the overworked fire dept. can never put out in time. Well, maybe don't think of yourself like that since it's probably not healthy, but it's the general idea. The other jungler will be frustrated, underleveled, and most importantly, unable to gank. Encourage your teammates to ward, something I type at the start of every match now is a variation on "Hey guys- if you need a gank, back up and play safe til I get there. Please don't die alone and then scream at me". This usually gets the ball rolling with some humor/empathy from the other lanes. Make sure to stroke them off with a short line of text whenever something remotely positive happens that could be construed as a result of their action, it builds confidence and momentum, while staving off the inevitable ragefest all losing games become.
Why play Hecarim? Initiation, Displacement, Disruption. Hecarim is blessed with the ability to gank a pushed lane by running fast enough to only take one or two tower shots while ganking from behind the turret. If you want to play a carry jungler, play Nocturne. If you want to be a big fast sack of meat that slams into teamfights while giving no fucks and tank carrying games, Hec is your (horse)man. Make sure to ad-lib plenty of jokes about hooves.
In closing, Hecarim is a member of the church of One True Build, a situation forced on us by the current ad-heavy meta. Hecarim has the combination of Rammus' mobility with Mundo's healing properties, while being able to do a little bit of damage and *initiate* and *displace* better than almost anyone else, especially those two sorry shitbags.
Currently 7-0 with Hecarim in placement elos (1100-1300) almost all while solo. I might put something together that is a little more cohesive of a "video guide", but for now have a quick look at a replay which focuses on the early game, which is by far the most important stage of a jungler's game.
http://www.leaguereplays.com/replays/match/2747840/