Since soccer is synonymous with the feet, footwear is the most important item you'll buy for a youth player.
Cleats are the mark of a soccer player, and they facilitate safety and efficiency of play.
Study the offerings. There are many types and styles of cleats. Cleats should fit snugly, with no more than a thumb's width of space between the toes and the front of the shoes. Remember, leather stretches and then molds to the foot. Choose looser-fitting shoes for young children so that the cleats don't affect the growth of the feet.