L. Homer answered:
All I can suggest is to try a practise square and count the number of stitches and rows for each type of yarn and decide on how big you want your squares.....It is best to keep to the same type of yarn when ever possible because it`s less hard work. May I also suggest to make a small frame made from a piece of wood like a thick ruler with four nails knocked in 5 inches apart or 6 inches apart at your choosing, so when you sew you squares together they will stay the same through out your work. I manage six squares of knitting at a time on this ruler. Just hook the corners of your knitting on each nail wrong side up and sew the seams. I work into a 9 square block, then decide on how I would like the colours to even out before putting the whole blanket together. You can make this ruler smaller if you want to work in a four block by just adding three nails. Good Luck, let me know how you get on.