Myth: Your wards placed has effect on your ranking
People say to supports that if you ward well you will likely get an S rank. Not true, you can spam sightstone in spawn and they wouldn't make it that easy to cheese an S rank with 200 wards placed and 5000 vision score. I thought this was obvious but the fact that I've heard this 15+ times says otherwise. I'm not even sure anything vision related plays a role in your rank, and if there was a stat that would it would be wards cleared (I honestly doubt it has an effect though).
Tip: I'd say the best way to get an S with support is to steal your ADCs cs for a game. Since rankings are based on the average of that champion+ role, most supports are going to have ~1.5 cs per minute, if you have 5 times that then you will help your grade a ton. This is how I usually get an S+ on Bard, I end a game with like 100 cs. I don't recommend this in ranked ^