To answer the OPs question. Depending on how much cash you're willing to spend you have a few options here.
1.) Buy a hypercrate of packs. Sell stuff from the packs individually. This takes a lot of time and a lot of cash but you get tons of credits. You also get some stuff that you can keep for yourself.
He said he has ~1500 CC. Did you even read the OP? How is this any kind of good "advice" on what to do with 1500 CC?
Edit: Doh! Andryah got there first.