I would divide into 16 units, and sew all pairs together, then into a 4-patch, then into 4-patch again , then the one big 4-patch, pressing seams so they nest together. I usually have a plan, which way I need to press my seams so they nest together nicely, before I start sewing. I like to cut the threads when string piecing, and arrange them between each set of chain piecing, using a leader and ender between each line of chain piecing.

I did mine in quadrants also.... But the 2x2 black plan may mke for better seam matching.

http://quilterscache.com/C/CarpentersWheelBlock.html

This pattern shows sewn in rows.

I sew in rows. No particular reason outside of that's how I read. Row 1, then 2 etc.

This is good. You now know, or have learned, how you best put things together. I'm a line sewer myself. Tried the quadrants, and I just couldn't make the concept work. Went back to the lines/rows, and I was back in my element, everything went together, matched, turned out square, lined up, all perfect. I ended up taking apart the section I did as a quadrant and putting it into lines, and that fixed the problem. I guess some of us work best in lines, some in quadrants, and I suppose some are revelling in this "quilt as you go" so they can do it a piece at a time. Whatever floats your boat!

I do a good deal of winging it anymore. Sometimes, right or wrong, you have to follow what is up in your head. Most times it works out well. I always keep in mind that there is not a known Quilt Police force and I can do what I want. Your block is very nice, by the way. And I am sure it will look great when you are finished.

Check out this site. It also gives dimensions for larger sizes.

http://quiltfrog.com/fourhour.html

Any way you sew it will be beautiful. Love the colors.

good morning. I like to stipple so I would probably stipple real small on the white. That really makes the dark pop out. cool effect try it on a sample piece. If you don't stipple, stitch in the ditch would be nice as well.
Dawn