League-of-legends – When is it important to counter-jungle over ganking

Yes, it's worth it to pick another jungler. It does not necessarily have to be a counter-pick though, which probably needs some explanation:

• The advantages you gave for having a jungler hold for your team as well.
• What you labelled as 'more effective' does not really require a jungler at all (coordinate your team to kill the enemy jungler [wards!] or steal a buff)
• Your downsides are too situation dependent:
  1. If behind enemy lines, you better know what you're doing. You have to be sure that your champ can live up to the enemy jungler and you have to make double sure that all other enemies are on their lanes. While it is a downside, it's one for which the risk can be dealt with.
  2. If their jungler is higher level than you, then either you have to improve your jungling, or you got killed/hindered before. Shouldn't happen for the first creep round, unless someone messed up their early game (see below)
  3. same as 1. Do not get killed in the enemy jungle. The enemy jungler shouldn't be able to kill you (or you shouldn't enter his lair!) and if you get ganked it's your fault for losing track of your enemies. If you suspect only a single enemy missing that might come for you, you better be on your way back to your jungle.

Anyways, double jungle teams are quite a common thing, because neither team wants to ignore the advantages gained by having a jungler. However, it also means that your team should know how to deal with that situation. Here's a few tips for general two-junglers-play:

• Prepare for more ganks on both sides. For both junglers it's usually safer to gank, than to visit the other side's forest.
• Make your jungle starting save. Not getting harassed while you get your first buff is extremely important. The team should realize this and protect you. Place your mates into the forest access points near the river to watch out for early ganks. Only let them leave, once the buff is save.
• Of course, you can turn this around too and try to gank the enemy jungler with your team. Not just a single counter-picked champ, but 2+ champs.

As you can see, two junglers are possible, do make sense, and generally lead to very fast and intensive gameplay. Beware on random groups though, as a two-jungler game demands a lot more from all players and failure is easy to achieve in that setting.

My question is: Should i switch to a jungler so that we have one, even if it means missing out on farm for my team?

Depends on the draft pick order, if you are a good jungler and you are first pick, you can pick one immediately; if you are not first pick and notice the enemy team has already picked a jungler, you can ask in chat if anyone is jungling. If not, it is recommended that your team has a jungler as well, then top lane will be 1v1, you can control the Dragon on bottom lane, and you can set up ganks.

What soft skills do i need as a jungler, e.g what should i pay most attention to when going into the jungle?

You need all of these amongst others:

1. Map awareness: Control (a.k.a) warding the river sides during early game usually after your first blue pill, doing so will prevent your bottom and top lanes of being ganked. Warding strategic places during mid/late game can win fights, baron and some of the enemy jungle bushes or even your own jungle bushes.
2. Wise use of Smite: If you are going to jungle, you should almost always have smite summoner spell with you (very few exceptions here, perhaps Nunu), it will make your jungling faster and you can also kill Dragon/Baron faster having the possibility of kill stealing if you are aware of the enemy team killing them.
3. Lane awareness: One of the most important things a jungler should do is besides killing the neutral creeps and roaming around, is setting up ganks / denying / defending turrets; whenever you see any lane is being outpushed you must leave jungle and defend the turret while the laner pills back, also harassing mid, by just making the enemy mid laner blue pill back will make your mid lane gain more exp/gold by killing creeps alone.

Probably another question, but what else can i do to carry harder? I mostly only lasthit and that means playing safe and not getting many kills mid in favor of harass.

Last hit is a very important thing to do overall, not only carries should do it, however you can easily harass while last hitting, it just takes a little bit of practice and knowing exactly what your champion skills are. In order to effetively carry, you should just play smart and aggresive when possible during team fights and laning phase, meaning letting your tanks engage and start the fights, targeting the enemy AD/AP carries. Also a very importing thing a carry should do is pick items accordingly to what the enemy team comp is, perhaps maybe just stacking AP flat items would not be the greatest idea if the enemy team is heavy on MR, stacking AP + Magic Pen items would do much better, same idea applies to AD carries; additionally if you as carry are having a good early/mid game, you should also buy some defensive items, such as Guardian Angel / Banshees Veil in order to have a little more survivability.

Useful links:

• Stonewall Jungle Mindsets, check out especially Warwick's mindset, it answers your first 2 questions in a pretty good and clear way.
• Delepitore's Comprehensive Guide