From Craftsy:
Leggings are a basic for all seasons! Don't bother buying them at the store when you can make them yourself. These leggings are not super tight so feel free to go a size down if you want them to fit snugly. Knit interlock or jersey are a great choice for these, especially fabric with a bit of lycra.
Visit my blog for tips for sewing with knit fabrics and for a complete photo tutorial showing how to sew these leggings with a regular sewing machine or with a serger and coverstitch machine.