The most difficult thing about sewing knits is fighting the curl. You know how the cut edges of knits curl up and are a bear to keep flat while you try to keep your seam straight and sew. I never have enough hands! My son wanted to make a pair of shorts, his first pair by the way, out of a knit we found on the clearance table. It curled horribly. He'd never be able to keep the pieces lined up and flat. After looking around the house a bit for something to stiffen the knit....ah ha. Spray starch! Yep, it's that easy to flatten your knit for sewing and then wash it out. Some knits take more than one application to get them flat, like woven, but it works like a charm. Even my little guy was able to sew his first solo project on a knit without the slightest curl.
Hot iron (no steam)
dries the starch. Move to the next spot and press. When your sprayed piece is dry it shouldn't curl.
The pieces in the picture are for a dress that Curly is getting ready to sew.