Buy as many cheap players as you can with more than 10 contracts and more than 90 fitness in order to resell them then more expensive than the purchase price. Buy the player at the lowest market price (or up to 300 coins). If you can not find this price, go to the next player! Do not focus on a player, there are dozens and dozens of others.
Avoid purchasing the same player several times at the same time, thus avoiding losing too many credits in the event of a fall in the player's price. The goal is to have a list of up to 100 different players.
Put your players on sale by listing them 1 hour. The goal is that your players appear most often in the first pages of the results. This is why they must be listed for 1 hour and relist as often as possible (via Companion application for example).
Indeed, a buyer in a hurry who wants a player will only look at the first pages of the auction. Even if your card is a bit more expensive than the competition, it will already have some contracts, a good shape and even a style appropriate to the player. The buyer will therefore be more tempted by your card.
Do not hesitate to consult the profit schedule. The more profits you make, the less you sell players every hour.
The Tech Crezip works on the same principle as the FUT Millionaire tech, except that in addition to having more than 10 contracts and more than 90 form your player will have a style suited to his post.
I do not mention here the Hunter, Shadow and Catalyst styles that are more expensive than the others, and therefore rarer. However if you find a player with this style, do not hesitate to resell it a little more expensive than expected.