so i am relatively new to the game(level 21) and i really like playing jungler. but i've read that one of the jungler's main roles is to ward as much of the map as possible. so i buy items like trackers knife 
to help me get vision. but when i watch pro streamers they usually carry around just control wards and oracle. i am now very confused as to what to buy for wards. Do i just carry around control wards? if so where do i place them? any help is appreciated.
I usually throw a control ward in the Jungle bush on bot, or on the river bush below mid. the Oracle is to disable enemy wards so they don't see you about to gank on the minimap.
Hi Shock16!
I'll try my best to help you out mate!
So, as a jungler you build one of these: 
I bet thats not new for you.
But, i guess you did knew that you can upgrade the one you bought!
These give you buffs to this item.
Lets you use smite on Champions. When smited you get 20% less dmg from the target and deal truedmg based on your level with Autoattacks. Also, you get sight on the target for 4 seconds.
Also lets you smite champions. The target gets truedmg based on your level and gets slowed by 20% for 2 seconds. Nice for ganks, huh?
Is the tactical tool you search. With this, you cannot smite champions. Instead, you get 2 Wards when visiting your base. Now you can ward for example dragon or bushes for your lanes when passing by.
Also you now can get 
and 
to manipulate and eliminate the enemys vision. You get 2 wards on your knife on-the-go! When you got the hang of it, these tools are pretty powerful. Dont forget that you can buy the next level of your knife item!
Choose, what fits the best to your champ.
Any more questions? Try it out! Just ask, if you want more information! I'll be here to share my knowledge as good as i can.
Play with honor, play fair. Have fun!
Lulu4life <3
-SRB Toad 
Well, any champion really should be warding. So it's not only jungler's job. You shouldn't stick with only, remember that you have trinkets + you can get control wards. Placing them in bush in the center of river is good, but you can also place them in enemy jungle bushes to have vision of their camps and them passing by too so your team knows where their jungler is and can prevent being ganked. Jungler's mains job is ganking as well, that's why sticking only to isn't very good, as you might lose fights/do unsuccessful gank because you weren't able to smite player with or .
It doesn't mean vision is not important, warding is still key.
The point of vision is to keep track of the enemy team (mostly jg, since they are going to be mia most of the time). SO, you want to put wards where the enemy jg is most likely to go....big intersections, camps (especially buffs), etc.....as a jg, you will know/learn these spots better than most.
As a supp main (once I get enough gold), I always keep 3 Pinks on me. Don't just use them for a one time placement...use them to get rid of known enemy wards as well....75g is cheap compared to the 450+ in death gold. They are also good bait..."accidentally" place one outside of a bush. People can't resist standing there hitting it for 4 shots...AMBUSH!
Also, you DON'T have to ward in a bush...remember yellows are invisible once placed. Lots of time you can get more angles of visions if the ward is out from a wall a bit, which often means....not in a bush.
When you're playing a game Imagine your on the enemy team.
Where would you ward?
No matter what your elo is the enemy team is going to think similarly to you.
If your ganking left and right chances are they are warding every bush in the river.
Place your control ward In any of those bushes
