You see the wave right at your tower you decide now it is my time to strike.... IT IS THE PERFECT TIME TO GO NO OTHER TIME BUT NOW!!! WTF MY TEAM ISN'T DOING ANYTHING THEY ARE ALL NOOBS!..... If this sounds like you raise your hand. Now that we have a count of how many of you are noobs we can now get started on some actual learning today. When you decide to jungle you take on a very different role. Your job is to gank when needed (not to be confused with all the time) now think about when you actual gank do you A) Gank when the creep are at the tower or do you B) Gank from the bushes when your team is pushed or C) Whenever you feel like ganking or D) When they tell you to gank. Jungling doesn't work like most people think you cannot just gank at the sound of a button and you cannot expect to successfully gank every single time. Your time has to inform you of things that might have happened such as did Cait use Flash within the last 3 minutes? Have you noticed if Sand King leveled up Sandstorm?
These are all things you need to know before having a easy gank. If Cait hasn't used flash you need to position yourself in a way that will stop her from going the way that will save her. Did you bring a sentry or dust for Sand King when he uses Sandstorm. If you cannot land the gank successfully you wasted time that you could of used to farm levels or items that may help you better with ganks or you missed a time that you could of stole blue or red from the other jungler. In the end it does help your lane but if you completely whiff it or spend 30-60 seconds just sitting and waiting you are wasting time that could be used for better things.
Just like supporting it is something that require positioning and talking to your teammates. If you say you are going to gank then they decide to go back to base they didn't really want you to gank and even if you did you are likely to not be successful in the gank. I've seen so many players go for a gank when the creep wave is at the tower and now the lane has to bit the bullet and take hits from the creep as well as give away that a gank is coming because you couldn't wait until the next wave came up. Your lane also has to be willing to work with you because this happens a lot too you are about to gank when Vanye decides to leap forward and scare the enemy back and now they are further along and you decide I'll still go but now they are out of position and closer to their tower. This is the worst time to actually gank because now they will be more mindful of the gank and be prepared for it because Vanye is being too aggressive in the lane than normal.
Now this also happens a lot you have an Udyr waiting in the bushes while your lane creep are right by their tower and it slowly starts to push toward you again when he just runs out and decides we aren't close enough to the tower to get any aggro. Then Udyr hits once or twice and claims that you didn't do anything to help with the gank so he decides to tower dive at level 3 or 4 soaking up two or three hits from the tower and dies. So he complains that he isn't going to help you with a gank again so now he fed a kill to their team as well as died so he lost 30-60 seconds worth of jungle time that could of waited for when their creep were closer to his tower. Now I've been talking a lot about League of Legends so let's move to Dota 2 for the rest of this post. Before I leave this topic though NEVER gank from the lane always come around if there is a ward pay the 200 gold for the elixir to be able to see wards.
Unlike League of Legends it is way easier to gank in my opinion. The only way to fail at ganking is if you are a horrible ganker or decide to go for the target that could easily escape. Dota 2 is more about position and know what the opponent can and cannot do like Earthshaker cannot blink away before 10 minutes unless he has great amount of farm. This means all you need to do for a good gank is come up from behind the lane when it is pushed and just corner them into a position where they will just die. Most junglers in Dota 2 have a stun or slow so make use of it when you think they are more likely to get away. Don't use Enigma ultimate unless they will escape because if you don't need to waste it don't waste it but if you think at any moment they will run away drop that Blackhole. Only takes around 3 minutes to come up and it takes them about a minute to come back to the lane so well worth the wait just to do it again in 2 more minutes.
Dota 2 you need your lane to work with you either with moe slows coming from the support such as Crystal Maiden or maybe a stun from an Earthshaker. Even Warlock's slow works wonders when you want to gank it could even bait out the enemies stun to stop them from doing anything and this creates the perfect time for you to come from behind and earn at least one kill for the team. If they have wards or you notice any odd movement just turn around and wait a minute and come back because if you see something odd it is likely odd because they see you. I know plenty of people that play Dota 2 and right away they can feel a gank coming and that feeling can create tons of problems for a ganker when there actually isn't a ward they just know normal timings and positioning to say "hmmmm something isn't right". It only takes a slight change to feel uneasy or the need to ward so when you get that feeling trust it don't let it pass by you because you think you are wrong. If you think you are getting ganked and you checked the map you are likely getting ganked sooner or later so pull back and wait for the wave to come to you.