I decided to do a simple pencil or straight skirt using an over-sized men's shirt I found at Wal-Mart for $5.
Step 1: Trace your skirt
Lay a straight skirt that fits you well on top. Make sure that the bottom of the skirt lines up with the bottom of your t-shirt. This way your skirt bottom will already be hemmed and finished.
Trace leaving a 1/2" seam allowance all the way around.