Before you do anything, go to the EDIT mode and change your opponent's goalie's "Goalkeeper Skills" to 1.
Get fouled in the edge of the area, towards the centre (see GreenBeretEater's solution on how to get fouled easily).
Aim straight to the open area beside the goalie, and hold DOWN on the d-pad and hold the shoot button to FULL power. The ball will roll around the ground and go in under the wall, as they'll jump when it's coming towards them, and past the goalie, who will rarely attempt to save it because of his low stat.
Also, my first free kick came off the goalie and my fifth one went in off the post, and the achievement popped.