I know this is an older thread...But, this may help someone out there... I am about to do a wall hanging with multiple stip piecing, so I've been studying up lol
1)As a few have said, Sew your strips together from opposite ends/or every few in opposite directions..exmple- sew one from the top down, the next from the bottom up
2)Also, until you have it down..Try sewing no more than 16 or so strips together( or less)...Even if you have to sew mulitiple sets...
3)And as always, Press your fabrics in all phases with meticulous care so as not to stretch you material..
4) Make sure your stitches are closer together so your strips don't unravel as a few have mentioned.
hmmmm, that's all I can think of as of right now- will add any more hints when I reference my books...