Another route to help build your team up is the new FUT Draft
First of all, you must make sure that players are put in their correct position, as it will be impossible to create good chemistry otherwise. As long as players are in the correct position, the chemistry is largely is based on three things, the players' nationalities, club they play for, and league they are in. Having none of these in common with the surrounding players will be shown with a red line between each of them.
By having players beside one another that share one of these, it should create a yellow line between those two. By having two or three shared, it should create a green line, meaning you have the very best chemistry. This is where you will end up moving players around to try and get the best chemistry all around. However, as we said above, do not start moving players around to the wrong position to try and get players beside each other that share one of these three factors or you will be in worse shape.
One of the hardest things to do in FIFA Ultimate Team is to have a perfect roster of players that share the aforementioned factors. As a result, there is an alternative that you can do by basically splitting your team down the middle. In this one, you can have players from all around the world, but you must make sure that they share commons leagues or clubs. By making sure that players are in the correct position, you can focus on watching that the left side and right side respectively have high chemistry.
This level of chemistry is shown by connected green lines here on the right and left sides each, though getting green lines between the two sides is less common. You can still do it and might need a few, but at least work to get yellow lines. By doing this, you can still get a 100 chemistry rating with a few non-green lines.
Another route to help build your team up is the new FUT Draft, which is one of the best features of FIFA 16. This mode does have an entry cost sadly of 15,000 coins in-game, but you can also get some big rewards by playing, including coins and new cards. The better you do, you can get huge rewards that can help your team, though you will have to once again be careful to make sure these better players fit into your team's scheme to keep the chemistry high.
Overall, it's certainly going to take some time to build a real quality team and earning coins is a big part of that as well, so make sure to check out our other guide on how to earn coins quickly in the early goings of FIFA 16.