The following steps will help you to fold T-shirt:
Lay the t-shirt flat.
Draw an imaginary line across the middle of the t-shirt.
Pinch the fabric at a point on the line a few inches in from the edge.
Draw an imaginary line from the pinch point to the shoulder seam.
Use your free hand to pinch the t-shirt at the point on the shoulder seam.
Bring the pinched shoulder seam to the bottom of the t-shirt.
Use the hand pinching the shoulder seam to pinch the fabric at the bottom of the t-shirt so that both the shoulder seam and the point on the bottom are pinched between the thumb and index finger.
Uncross your hands and lift the shirt.
Fold the loose sleeve under.