Hello board. I recently came back from season 4. A lot has changed but one thing has not(sort of): wards.
One key component to my climb through that which is called hell (encompassing all of ranked levels of play) was my ability to discover the true power and benefit of wards.
Let me explain a little
1. 2 wards nearby to each other typically are better than a single avoidable ward. For whatever reason.
2. Placing wards in the enemy territory will tell you more about the enemy team, more frequently than those in your own jungle.
3. Well placed wards 'can' allow you to safely do things like split push(is this still viable?), baron, un-turtle into your own jungle, see when the enemy team splits up to farm. Etc.
Generally, from my own limited expertise there are roughly 2 sets of good combo wards to place. One set is in the enemy red-buff side and the other is in the enemy blue-buff side.
For red-side I place one ward in the bush that precedes raptor, the other in the bush attached to the opposite side of the tree "wall" from there. So it would be the bush directly north is the enemy starts on baron side, or directly south if they started dragon side. This allows you to see way more than it should as the enemy has to come through the middle 'cross' section to be unseen as your minion waves if pushed out will reveal them at some point if they take either of the two neighborong lanes.
The blue-side, while I believe is typically inferior to the red-side wards still allows you to see someone grabbing the blue buff and also can pay off when considering dragon/baron as it is very easy to "catch" them in retreat and not find yourselves 'caught' while you pursue them (should your team choose to). These two wards are placed roughly as follows. One by the blue bush, typically slightly out of it so it can see down the long path towards their base but still able to see slightly in the direction of the Wolf camp. The other ward is placed in the bush between the Wolf camp and their mid-outer turret. The one closer to their base.
With these ward sets you should find several frustrating strategies to be futile against you and your unconscious team of zombots. One, you won't all head to baron/dragon and then mysteriously get baited into an ace. With these wards, never. Two, if you are turtling and not sure where it is safe to farm because they all left your teams vision for a supposed baron/dragon then I would reccomend checking this set of bushes with wards on your side. I have found many a garen hanging out in my red-side bush (the second one that is farther from raptors). Typically one or two are waiting behind while the others head off to farm various things and if they catch you guys coming out, they head straight back to your base for more gold.