Very simple, very easy!
I raided my 2" strip bin for dark and light strips. There needs to be enough contrast here to read as dark/light in the finished quilt. I threw out some strips that were just too "medium" in value to fit in either category.
Sew them together as strips.
Press to the dark.
Cut in 2" units.
Pick two at random and sew together.
A few hints that help me:
1. When sewing strips together, just pick a new strip of the value you need and add it in there. If two strips run out at the same time, start with two fresh ones.
2. Chain piece, chain piece, chain piece!
3. When cutting 2" units, you may need to square up your edge from time to time.