To get a hat-trick you need to score 3 goals with one player in a game. This is quite easy as you can see the player numbers above the players when they are selected so just score your first goal with anyone and take note of his player number. Then just keep passing the ball to this certain player and make two more goals.
Making goals in this game is really easy. You just need to go near your opponent's goal and swipe towards the goal. You should swipe ALL the way to the goal and not just leave it at half way. If you don't swipe all the way to the goal then the ball will just keep swinging to the direction you ended the swipe and you will most likely miss the goal.
I got this achievement in my first friendly game during Pre-Season 1.