Clearly you don't want to fall behind in levels, so you need to farm your creep camps, but what do you do when your lanes are clamoring for a gank?
I have this problem especially with junglers like shaco that are supposed to be good early gankers, I end up too low level. Or, sometimes with Udyr I will only farm and my lanes end up dying.
Best Answer
Ganking junglers (especially like Shaco) have a particular risk when you select them: If you don't gank successfully, it's difficult to be effective for your team. Being too low level in mid-game is one of the symptoms of that. Being under-geared is another. On the other hand, farming junglers can give you tunnel-vision inside the jungle and keep you from ganking lanes.
So, to answer your question, it depends on the jungler a little bit. Shaco you definitely want to be ganking whenever possible (your team, by the way, needs to make this possible). With Skarner, ganking is good, but before level 6 you're often better off farming unless someone has over-extended. Shyvana you'll be spending a fair amount of time in your enemy's jungle, which takes away from ganking time.
Generally, here are the order of operations you should be following:
The only remaining question is what to do about buff's. In general, you want to get/give your buffs if A) nothing is going on, B) you're being counter-jungled and you know you'll lose it, or C) getting that buff will help you get a kill in lane (red on Shaco/Lee Sin/etc.). Buffs are very important, so make sure you fit them in with the above.
In short, the biggest thing you can do is always being doing things. Junglers are in a unique position of improving the team's overall gold by helping lanes win.
Jungling is a complex role, so I'm sure there will be comments with more/different advice.