Do not show yourself on the map to the enemy if there is no reason to. People like me, will take advantage of knowing where the enemy jungler is. "oh the enemy jungler is camping bottom. Say goodbye to your red/blue buff"
I personally think first drag is overrated, especially if you get a timer on it. I always say, best part about drag, it will be back in 6 minutes. Many times teams will basically suicide just to get that first dragon. Sometimes it is worth it, usually it is not.
The best tip I can give, know your enemy jungler, and counter him when you can. If I can counter the enemy jungler, I will counter jungle him every chance I get. If the enemy is going amumu jungle, he will start on his blue side. and if you can somehow steal it, you can set him back greatly.
As far as ganks go, I always like to remind my team at the beginning of the game. If they overextend and force the enemy under there tower, they will most likely not get a gank because I will not tower dive. Remind them of this so they do not get upset with you at the end of the game, complaining they never got a gank.
Personally, I like to get my jungle item complete and boots complete before I get sightstone. That's my personal preference however, it all depends on how the game is going, and who I am against.
I am no where near a "pro" jungler, but these are the things I have learned from other people that are much better than I, and I am just trying to spread the love.
Youtube/Twitch channel junglers that I watch:
Trick2g, my favorite one, he's a cocky asshole, but he does know his stuff when it comes to the jungle and what you need to do
Foxdroplol
There are many others, but those are my favorites
Hope this helped, good luck!