The key to a perfectly clustered Christmas tree is to use a variety of ornaments in different shapes, sizes, and colors. To create a balanced look, start by placing the largest ornaments at the base of the tree, then fill in the gaps with smaller ornaments as you move upwards. Use a mix of plain and patterned ornaments to create visual interest, and don't be afraid to experiment with different combinations until you find the perfect look. Don't forget to add some tinsel and garlands for a festive touch!