its just like any other marketing in real life, but heres the best tip i can give you, make sure to check the "cheapest offers" box then hit search, find a really cheap item, im going to give an example, Elf force and its 60% off, click on it to show all of that item on the market, lets say the cheapest one is 6,000 but the regular price is 15k. ok so the cheapest is 6k the next cheapest is 7k, next is 8, and the next is 9k you can buy every one of them that is cheaper than 15k and then resell all of them for 13k, so you buy the one thats 6k thenthe one thats 7k, 8k, and 9k, then the only one left is 15k or more, then you resell all of them for 13k so they'll still get sold and youll make profit off of each one, pretty much youre eliminating the cheapest prices so people have no choice but to buy them from you for a cheaper price than from the shop but higher than they were previously posted for.