I can't suggest a place for a tute but I don't think it matters whether you do the side strips or top strips first. I usually do the sides then the tops. Side strips would be cut 6" X 2 1/2" and top and bottom strips would be 10 1/2" X 2 1/2" to finish with 2 inch strips all around. Since you don't say how the sqs will be put together as a quilt I would suggest the approximate yardage needed for your 48 squares is 3 to 3 1/3 yds just to sash the squares. When the squares are sashed, how are you putting them together-will you need additional fabric to separate these new squares? Hope this gives you some direction. I'm sure someone else will also have some ideas.