GP is probably the currency most will go for. In the beginning, pretty much everything you do in the game gives you GP - simple things, like a new feint or using a different tactic will give you some hundreds of GP.
Every time you complete a game in myClub you will also earn some GP - even if you lose.
You can use this to renew contracts, hire managers, bid for scouts to get the players you want or try your luck with an agent. Keep in mind you won’t be able to get weekly Featured Players with GP, and your Managers will be lock if you are not get their required points. So, keep minimum GP everytime..