I am going to evolve it into a Glaceon.
You need to train it in special attack for sure. The next choice is your's. Either run speed or HP for bulk. I would recommend HP to compliment its nice bulk. It can use speed evs but it is naturally slow.
Since Glaceon is a generally bulky Pokemon, 252 HP / 252 SDef / 4 Def would be the best spread, in my opinion. It takes advantage of it's already pretty awesome base Special Defence and provides it with the well needed HP that it misses out on.
252 HP / 4 Def / 252 SpA
That is what I suggest