Counting has never been my strong suit.... 3 on 2....?

Ok. Well for the past year or so I have had the beginning of the Rachmaninoff Prelude Op 23 no. 2 prelude memorized. There is a difficult interlude section which is 3/2 right/left. I can usually solve it easily, but the pace of this piece is so fast for whatever reason I am having trouble counting out the 3/2. Whats a fail safe way or is there a saying to playing 3 on 2?