You need to farm rests through vids, around 20 a day will see you fine. They are the key to playing this game without spending money.
You only need 13 first team players, the rest are low * bought for 1 token and sold on negotiations.
If you can pick up a high 4* 18 yo you can train a SA and /or another position and then up to 6* for around 150 greens.
Once he is up past 100% he will get 2/3 of the way to 7* through the season and so will only need about 40 greens at the start of next season to take him to 6* again.
A player like this will last 4 seasons before his training starts to slow.
Add in a couple of Scouts each season (you have the tokens) and this is the basis of a squad