Although seasoned FIFA players already know this tip by now, new FIFA 18 Ultimate Team will be glad to know about this great way to make easy coins at the start of your UT campaign.
What you need to do is basically use the EA FC Catalog to buy FIFA Coin Boosts. This requires you to have a high-ish level in the game to obtain all the boosts. These boosts allow you to gain bonus coins (up to 1000) after every match you play in Ultimate Team, both offline and online on top of the existing coins you get.
This will come in real handy at the start of the game when players are cheap so you can buy some players that are in-demand and sell them later on for huge profit. Do note that coins will be sparse at the start of the game so the quicker you take advantage of these bonuses the better.