1. Depends on champion; (1): If your clear is fast you can do Buff then do Gromp,wolves or chickes if starting on bot. after you get lvl 3 (try to be full HP by smiting the camp before you hit lvl 3) move to the best gankable lane. (if started bot -> go to top or mid) (if started top -> bot or mid) The faster you clear, the earlier you can gank. Also make sure to gank a lane that won't lose even with a kill advantage because you wasted time/money if you do so.
(2): If your clear is slow you can clear the entire jungle and wait for your essential items or lvl 6 to gank. Make sure you pick such champions only when you can assure your team won't need you before you can get items/6.
As a jungler you are not, what people will always try to tell you, supposed to gank hardly lost lanes where ganking may even result in a 2 kill profit for the enemy. Also, always deepward when you see the enemy jungler out of his jung. Having vision on him will not only help your team, but you too will be able to react in time and make sure he doesn't kill your laners.