9-patch blocks can be made a number of ways depending on the look you want. You can divide the squares into a certain color combination using light and dark or using various color combinations or you can create a scrappy block that is just a jumble of color.
If you are creating a basic two fabric 9-patch (as shown on the right), it is very easy because you work in sets of strips. We all like easy right? The first set would be a-b-a and the second set would be b-a-b or using dark/light combination as dark-light-dark and light-dark-light. This is explained better by looking at the picture below.
Strips are all cut the same width (for example 2.5") and joined to make two sets of blocks as shown above. Seams are pressed toward the darkest fabric and then each block is cut into units of the same size as the strips were cut (ie 2.5").
The units are grouped into three as shown on the right above and stitched together to make the block. Since the seams are all pressed to the darkest fabric they will butt up nicely together and make joining the units go together very easy and quickly.
Here is a simple quilt using this nine-patch block.
Basic 9-patch quilt with blocks on point