Warding is an essential skill everyone needs to master, even when you're not supporting, but most wards are purchased as the support role. There are 3 types of wards. Trinket wards, which last for 1 minute, Stealth Wards which last for 3 minutes and Vision wards which last until they're destroyed, but they're visible.
Vision wards(far right) are the only kind of wards that can be seen by enemies without using a sweeping trinket, or another vision wards, they take 3 hits, but reveal other stealthed wards.
This bush is most often warded(called tribush), gives you good protection from jungle ganks.
Central river wards on either side of Summoner's Rift is good for objective control ( Dragon and Baron ), it's good to remove wards with vision wards/sweeper before going for objectives.
Wraith side ramp bush gives you more control over their jungler, as you can see him earlier by warding deeper into your/their jungle, giving you space to be more aggressive. Best spot for vision wards early game.
Mid side bushes are safest bushes to ward when laning mid, they help you with jungler ganks while laning passively.
Ramp ward is best when you want to play aggressively on midlane, gives you more time to fall back if you're too far pushed.
River bush on either side helps you spot jungler ganks safely.
Very deep wards into their jungler help you push out towers without worries if you have huge advantage.