Use Manual Shooting to convert more tap-ins
This year, tap-ins are surprisingly harder to score, even when you're perfectly position with your striker and close to the goal.
For this reason, I always go for manual shooting whenever I go for a low cross. If you're new to manual shooting, chances are you will probably miss some sitters at first, but you will eventually get better and convert this type of situation easily.
After my player performs a low cross (by double-tapping "Circle"), I tap shoot ("Square" on PS4) and hold L2 + Left Stick to point the arrow towards goal. You will have some time between the cross and your striker hitting the ball, making it an easy goal (as it should be!) after some training.
My conversion rate increased drastically after doing this.