Grouting subway tile involves preparing the grout by mixing it according to the manufacturer’s instructions. Apply the grout to the tile joints using a notched trowel, ensuring it’s pressed in firmly. Remove excess grout with a grout float, making sure to create clean grout lines with a grout line smoother. Remember to wear protective gear and ventilate the area while grouting, and consult with professionals or refer to online resources for additional guidance and support.