Personally, I find it extremely hard to actually not buy sightstone. I'm pretty good at it (if my year in review is any indication, I actually warded more than challengers. Super proud of that because my warding game used to be weak, but I made it a point to work on it everygame) and I've been doing it for so long, that my play style has evolved in such a way that it really requires me to be able to manipulate / control vision. Trinkets just don't cut it anymore.
I would build SS first, but I used to rush FotM after that. I'm not sure what I'm gonna do anymore. I guess I could go back to S3 and rush FH lol x3