Sightstone is one of the first items you get as a support, usually a first back or second back item (its depennds if you are doing really well and you want to holdoff sightstone to get a sup item upgrade) but i usually have a build path similiar to this on
oor most utility supports (I build Braum slightly different but this is just a general build)
or
(depends on style)
First back
+
+
(
if you are doing great)
Second: upgrade your support item and get mobis, after you have mobis and sightstone dont be afraid to deep ward and get your own jungle full of sight.
Now next is the hardest part, its the items that you really need to build accordingly. The usual items are
<---Armor, MR, AP.
Chalice for Mana and MR, Glacial for Armor CDR and mana, Codex for CDR and AP. These 3 items are the base for almost ever good support item that supports should be building.



For the next item i HIGHLY suggest
<----This is a great item that can be built into a good defense support item
Or a split push item that allows you to put a squeeze on a lane 
One of my personal favorite items for late game will always be
It gives defense, a split push item to pop in a lane and leave, as well as a little MS boost when near turrets (great for avoiding pulls, abilities or even tower diving)