I usually buy 1 T-Credit, use MRPs for purchasing Single T-Credit with 126 MRPs to get 102 VPs, when I am short of VPs to achieve my rank.
When you don't need the VP's but want to expand your team, you can save them until you can purchase PSA's, CSA's or a SBuilder unit.
You can spend them on products in the TripleClicks store.
When you bid on any item, you get 1 AVP and 5 MRP per bid. You can get 500 Action Versa Points every month.