I made a Trip around the World quilt way before there were any "rules". I went by how much of one fabric I had to make a complete path around the quilt. The fabrics I had the least of I started in the middle and alternated light and dark rows as I moved outward. It takes a LOT of squares as you get nearer the finish. Colouring in the little squares on graph paper will give you a good idea for how much fabric you'll need.