Map awareness is probably the biggest thing you need to be on top of as a jungler, after map awareness id say positioning is next most important, even if the enemy is in a good gankable position, if your position is off when you go in, it can really make or break a gank. And remember that a good gank doesnt mean you get a kill, getting 1-2 summoners spells off a gank is actually a good turn out for a gank too, it means your bot lane has the advantage as long as they didnt have to use any for when they duke it out later after you leave.
And this part is just personal preference, but i usually run smite/ghost on nearly every jungler i play because of the utility ghost offers for ganking/mobility in general vs flash. For instance, you're going to gank top lane because enemy laner is pushed up to your tower, but you know they have it warded, with boots + Ghost + what ever mobility your champ has, even if they pay attention and see you because of their ward, you having ghost, which they will almost always not notice, will put you on top of them much faster than they anticipated, usually forcing a flash or a 2v1 fight for your team, and since ghost has a much lower cooldown than flash, if you burn it and dont get a good gank off, youll be better off than burning flash and not having that for 5 min.