A key point to make FIFA ultimate team coins is that the price of some good players will drop when TOTW comes out. The reason is that people will sell them to gain fast cheap fifa 15 coins to purchase TOTW players.
Be patient, once you would like to earn fast money, you will have to prepare lots of knowledge of FUT. Once you're patient enough, you will definitely earn lots of fifa coins. Just buy the squad and resell them after you play with them each night. Sell them for say 6 hours at the higher starting price just than what you've paid for.
Once they sell, you will earn bonus fut coins and once they didn't sell, you will still get them. You'll be surprised at how many FIFA ultimate team coins you would earn by doing this. Buy them at cheaper prices and buy the other players. Don't be stuck on your favorite players or keep all players till you own a lot of FIFA 15 coins.