well, its technically simply, buy low, sell high.
u can achieve those things easy. as example. if someon is selling his whole deactive, u actually will/can pay lesss than all items single are worth, if u buy all at once.
then there are from time to time people which make "[B]" threads and have a specific amount of TC. just try to sell a few items, which u got from the deactive sale.
the items which are not so common and wanted (like collectors stuff, trails, gradients etc. etc.) can be put on the market for a nice low price to get some extra tc.
as example, i could buy your whole deactive for 20k (not correct prices tho.) but its worth 25k. and finally im selling each piece one by one and get 30k out of it.
sure this takes some time, but that is actually how marketing works if u want profit.
otherwise just buy tons of low price stuff in the market forum, orc, chronos, glad. etc. and put it into the market... depending how much items u have they are worth 500k+ tc..
but this takes a shitload of time to sell them. because u have to wait to sell every single item in the market. if u got like 100 orc forces, and u sell like 1 every 3 days... it takes u a whole year to get it. but at the end u made like 200k tc profit.
if u want to make succesfully marketing u have to invest alot of time.
uhm i think that was everything important, that i knew from my old marketeer time thoo... if u have any question feel free to ask.