amazing pattern drafting site for stretch fabrics, etc; not sewing 101 but great info all over the place. This piece in particular is a WOW, wet-suit engineering taken to the next level by reducing pockets of air and making more close fitting
If you can't find a free sewing pattern that matches an idea for a sewing project you have, learn how to make your own pattern! This sewing tutorial teaches you just that. Pretty soon you'll be able to design and make your own clothes.
How to sew a knit neckline binding // the Megan Nielsen method
Cheap and Picky: But how to copy a pair of pants? You can't just lay them down and trace them. Enter the painter's tape. It is important to use painter's tape, or some other low-tack tape because you are going to actually put it ON the pants.