I keep all the vials that drop--useful for me, especially in dungeon runs or sometimes in pvp. Some of the drops I sell to npc (green ones mostly, or useless junk). Some of the rares I keep, and some I give to my guild members. Cards I also keep until I get 4 of the same kind, then play it, hoping to get some mech, least with the Jack cards, which are few and far between. Passcards I also collect. Dog tags I've kept much, but they've filled my warehouse that any I find now I immediately sell. Some I've converted for silver medals, which I've used some to get my ulti. Memory chips are great--free rp if you don't feel like going to pvp.