Before I actually begin giving in-depth guides on what to do, I'd like to introduce myself. (:

BACKGROUND:

My Name's Nero, and I play on the Garena Server. Despite many attempts to climb up the ranked ladder, I still remain in Gold V, and I have no plans to going any higher soon. So, you must be wondering, "Who's this scrub trying to teach me how to jungle?".

I've been jungling since season 2, and I specialize in Lee Sin only. As you can clearly see, having a bad team voids your chances of winning, regardless of your KDA, or how well you perform.

Even since the new map came out, I've been studying it intensively, scouting for potential jungle/gank routes, plausible counter-jungle timings, and dragon control. Not only does this involve many strategic and situational decisions, it also requires a basic amount of competency, which I assume all readers possess.

DISCLAIMER

:
The following guide only applies if you're up for the risks of getting first blooded.
This guide works best when only one or two lanes are losing. It takes many trials and errors and perfectly time and predict how your enemy jungler thinks because every individual is unique.

Finally, On To The Guide.

AD Junglers:
Eg. Lee Sin, Rek Sai, Master Yi, etc.
The runes I always use are AD Reds, Armor Yellows, Armor Blues and AD Quintessence.
"BUT WHY SENPAI??"
The more damage you deal to neutral monsters, the faster you clear the camps.
The more damage you have, the more effective you are when counter-jungling, both in terms of time expense and early game duels.
The more damage you have, the more effective your ganks are.

Therefore, I conclude my case that damage is an important factor especially in the early game.

"BUT SENPAI, WHY NO FULL AD RUNES THEN??"
Well, unless you feel like recalling after every camp or getting rekt in the enemy's jungle because you were too paper, I strongly suggest armor. Remember, in order to effectively survive throughout the early game phase, armor runes are an absolute must.

AP Junglers:
Eg. Elise, Amumu, Maokai, Malphite, etc.
The runes I always use for this case, are Magic Pen Reds, Armor Yellows, AP Blues, AP Quintessence. Don't ask me why, it's my default AP runes because I don't like AP-Based Junglers.

I strongly advise 21/9/0 for AD Junglers. The exact placements of the points are really dependent on your playstyle, and what YOU feel is effective. They don't matter really much, as there are no right or wrong answers.

For AP Junglers however, I strongly advise a 25/5/0. This is mainly due to the nature of AP Junglers. Short sustain and powerful ganks, which is why we want more overall damage output. Once again, it does not have a specific order because every individual has a different playstyle.

This is probably the hardest part because of situation-dependent it is.

Because I play Lee Sin most of the time, I can only recommend the items for him.
Starting Items:
Machete + 2 Pots

1st. Back:
Stalkers Blade + 3 Pots

2nd. Back:
Warrior Enchantment + Boots

3rd. Back:
Boots of Mobility + Safeguard Enchantment

Mid-Game Items:
Maw of Malmortius, Last Whisperer

Late-Game Items:
Spirit Visage and Randuin's Omen

Like I said, because items are extremely situational, you do not have to follow this build at all. However, I'd recommend it if you're using my specific jungle routes because they often sync very well.

Once again, because I'm a Lee Sin user, I can only share my skill sequence for this blind monk.
Start with E, and get Q next. From then on, Max W whenever possible.
"BUT SENPAI, WHY??"
W is one of the most underestimated skills on Lee Sin. People fail to understand the basis of Maxing W, so only me to enlighten all of you.
W when maxed on early levels, is extremely helpful in jungling and ganking.
Not only does it provide a 200hp shield at max level, it gives 15% life-steal and spell vamp, which is crucial in jungling and saving your allies *** from annihilation.
The next skill I recommend to max out first would be Q. The thing about Q is, it scales much better than E and does damage respective to your opponents' missing health. This is a duel winning skill in early game duels against strong junglers.
Your R should be maxed every chance you get, for it's your main damage output in assassinations.

I would recommend the default flash and smite combo. Nothing else.

OMG FINALLY TO THE MECHANICS RIGHT?

There are dozens of potential good jungle routes, but here are some I have done and are extremely effective in disabling the opponent's jungler to effectively clear camps.
Before I start however, please understand that ganking is not everything. Do not underestimate the power of your presence in lanes and enemy jungles. Sometimes the best defense is deterrence, so always remember to flaunt your deadliness on lanes, not necessarily ganking but apply the pressure enough such that the opponent fears you. Also, make sure you counter-jungle to ensure you have a headstart over your competitor, this is extremely beneficial if your opponent jungler has a strong early game but a weak late game.

ROUTE 1:

If the enemy starts Blue.
Start Gromp with a hard leash, make sure not to smite and tell your top/bottom laners to reduce the health of Gromp to around 200-300. This is important if you want to successfully screw your enemy over. Immediately after killing Gromp, you will reach level 2, in which you must travel to your enemy's red. Take their red and make sure you smite it. This is to reduce the amount of time spent in their jungle, and so lesser chances of getting caught. Remember to use your ward trinket. Place it such that you have visibility of their bird camp. Normal junglers should have about 50% health when they do the birds and your mid can actually get first blood that way. However, if the opponent jungler decides to back, you will not see him on the map anytime soon. Anyway, now that you healed yourself with that smite, your path will split into 2 different ways. You can either take their Golem and then proceed to gank the nearest lane, or return to your blue and continue your normal routine. That is, of course if you still have health. If in any case you are less than 30% health, do not attempt to perform risky maneuvers. Instead, recall and return to base. So if you chose to return to base, you should have enough gold to buy a stalker blade and 2-3 pots. 350g + 70-105g. Now you can either continue jungling or start ganking with that new blade of yours. I would not advise invading their jungle again, because many junglers have different routes and different timings, which means you cannot predict their health and the perils that follow along. However, you must remember to keep a look out at the red timer of their jungle. Because since they do not have it, you have complete control over THEIR red. Always prep a minute early before invading, you don't want to be caught with 20% health in their jungle. Get wards too, I would advise vision warding the empty area near the bird camp, so to ensure you have vision over the opponent's jungler's activities.

Route 2:

If enemy starts Red
If your opponents starts red, ensure that you are starting red too! You should follow steps given for Route 1, but vice versa. Instead of going their red this time, go their blue, ward the junction of the camp too! This is much riskier as I've seen junglers who smite wolves which can jeopardise your whole entire plan. However, if you manage to take their blue scot free, DO NOT attempt to take gromp, you'll get caught. You should gank top, in any case.

Dragon Control:
Nothing is without risk, so ensure you have vision wards prepared for this. Do it early without your opponent's knowledge and you will surely control it for the rest of the game. The best times to do dragons are when your opponent bottom is dead or very recently recalled. This is to prevent a huge teamfight from occurring unnecessarily. Be sure to have smite too, it is riskier to take dragon without smite without the knowing the exact location of the opponent jungler. Remove any wards before proceeding to do dragon, be it 1 min before or right before you're doing it. You don't want your enemy to have vision on it and moreover you don't want them to get the timer for dragon. If you are on the red team, remember to drag the dragon out of its nest before proceeding, as a precaution. You should do it every chance you get as the bonuses of it one of the deciding factors of who wins the game.