Whenever I'm planning my quilt/block, I find out how many of each piece/section I need to make, figure out how many pieces per section/block, pull out the fabrics I plan to use and divide the number of pieces needed by the number of fabrics I'm using. Most times it works for me using this method. The quilt I'm working on right now needed 18 blocks of the 2 blocks within the quilt body. I counted how many darks and lights, pulled from my scraps from the last quilt which I had planned to use anyway, then added more fabrics to fill the need plus a few extras. Since I was making this a controlled scrappy quilt, I laid out each block on my cutting table arranging each piece accordingly so no two blocks looked alike. Then I piled them into separate piles per block in the order they would be stitched on. I put an alphabet pin on the block and a matching pin on the pile so I wouldn't get them mixed up (I'm good at getting confused).
As I stated this method seems to work for me plus I'm using up my scraps too. Next quilt will use the brown scraps from the prior quilt I finished so I was able to use up most all the brown, blue and beige scraps from Quilt #1 on Quilt #2 and #3. The scraps from the Bricks & Stones quilt will be put into another quilt on the chopping block called Imperial Diamonds. Using the CT Mirage collection with some batiks I have.