In my opinion, the best way to use your TCredits is to go on auctions and bid for something you like.
Personally, I collected amount of credits I meant it will be enough to win an auction for TCredits and now I easily duplicate my TCredits. This helps me a lot to achieve ranks because we all can get 500 action VPs for bidding on auctions and also change MRPs to earn even more sales VPs.
