Here comes the fun part. Pick a nice sunny part of your house. Don't do this at night, the colors won't be true and you might have a "What was I thinking?" moment with the finished product. You don't need a huge amount of space unless your quilt is mongo sized, I just use our living room rug.
Stack the fabric squares into loose categories: stripes, solids, florals, prints, etc.
Start laying out the pattern. I rarely do a set look, what I am looking for is balance of color, pattern and light versus heavy prints and patterns. Sit back, walk away and come back to it. It can help to take a photo and look at it that way. I didn't like this, it wasn't balanced with the blue solids.
This was better. It never can get perfect, unless you use all store bought fabric, have the perfect amount of coordinating squares and have a set design. But that's not as fun as the jumbled, hodge-podge look. Once you settle on a pattern, go with it. After the quilt is made, it most likely won't be analyzed ever again.
This is the bottom left square. Take it and stack it on top of the square directly above it.
Now keep doing that all the way up the row.
What was on the bottom is now on top, the top square in on the bottom.
Do that with all the rows.
Make some number labels, and pin them to the squares in order. I have seven rows.
At this point you can either start sewing the rows together, or carefully stack them away for another time. For me, that will be tomorrow. There is no returning now, all the decisions have been made, the next process is sewing, sewing and more sewing.