It's not terribly difficult.
The absolute fastest a jungler can arrive to a lane is like 2:45, and that's if they are a hyper-clear jungle and head straight towards you. Generally speaking if you ward at 3:00 you're perfectly fine because you can place another ward and by the time the second one expires you're ready for your first back and can get a pink anyway.
Top lane:
Don't push like a retarded monkey and ward the bush closest to you. If you're red side you pretty much have to let the enemy laner push you in and ward your tri. Otherwise you will get 100% fucked by any half decent jungler. If you're blue, just don't push so recklessly that the enemy can freeze. Ward river.
Mid: Ward one side, preferably top bush (unless you know enemy jg started top side) and hug it.
Bot: you have two trinkets.
It really isn't difficult. Only exceptions being Zac (who is basically permabanned) and Eve who pretty much can ignore all wards.