Play more to earn more - that's one of FIFA 16 Ultimate Team
Similar to other EA Sports mobile games, you'll earn XP with each match you play and level up as you commit more time to the game. That's significant because the amount of coins you earn at the end of each match increases with your level. Cheap and fast FIFA 17 coins sell here
Most importantly, though, you get a nice-sized coin bonus for playing matches through to completion. That means that even if you're taking it on the chin, you should probably see the match through to the end. Your coin total will thank you.