There are many different types of stretch fabrics, 2- Way (has a horizontal stretch) 4 way (stretches both horizontal and vertical) lycra, jersey, knits, etc. When you look for a stretch fabric be sure to feel and tug on the fabric to see what kind of stretch it has, is it tight? does it go back to its original shape well? 2-way or 4 way stretch? I usually work with 2 way stretch because it is a little easier to get the seams and hems right. 4 way likes to curl alot more and will give you hell if you try to hem it. A regular straight stitch on your sewing machine won't hold it when put under direct stress~ A serger works great but if you don't have one be sure you get a knit/stretch needle for your machine. Triple Stretch Stitch~ is formed by a forward/backward motion of the needle. It makes a strong seam great for high stress parts of a garment such as the crotch or armscythe. Zig Zag Stitch~ This is great for knits that curl more Narrow Zigzag Stitch~ This is made by adjusting your machine to make the zig zag stitch closer together leaving less of a gap. Much like how you would do a satin stitch just not as close together. This works best for materials that do not curl as much. Taped Seams~ These are used in areas where you do not want alot of stretch. You sew the seam using twill tape or seam binding pinned over a seam line. (sewn on using straight or zigzag) Great for hems or seams that don't need to stretch.