How to play jungle as efficiently as possible?

I'm having a hard time understanding when to farm, when to gank and who to gank. I play with a few friends on ranked and I just can't seem to make them happy. I play jungle, one plays adc and the other plays top or mid. I tried listening to pro-players and read advice about ganking the lane that is most ahead or going for the easiest kill.

First game. My top player died level 2 to Nasus so I tried ganking a lot but was unsucessful as he just ghosted or ultied away and we couldn't kill him. That game, my adc friend was very unhappy that I didn't help him at all. I tried focusing mid and got him ahead but eventually the other jungler cam and made it even.

Second game. I tried camping bot lane as they were winning really hard. My top lane friend died a few times while I was doing that. I ganked once in a while when I was in my top side jungle top get him a kill but eventually, we couldn't even 2v1 him. Then, I just focused bot lane and tried saving the game that way. That didn't make my top lane friend too happy and his opponent started to just deny him cs by proxying.

In the end, both of them are just unhappy with me. Am I doing something wrong? Am I just ganking the wrong lanes at the wrong time?

P.S. I'm still new to the board. Please tell me if I posted in the wrong one.