Good system to unlock skins
Dulfy has a guide to finding the skins; she offers two methods, one cheaper than the other. I don’t know if you are referring to unlock method or to finding them in the first place, though.
Either start a new character or hop on one that has a lot of map exploration to go. Do every heart and any events you see. Buy any skins you need to unlock for cheap via karma, get area specific weapon drops from kills. Also get some different level armor drops for some different skins. Craft in all the professions for those skins as well.
Fractals are also nice because they can give you rares from any area, giving you a good source of skins from that.
Do EotM and get some badges to trade for skins. Buy cheap blues and greens from the TP that have skins you are missing and salvage them.
Thanks guys, you’ve given me some fresh ideas to work with.