Another seam finish that is good for light-weight, unlined garments is the French seam.  This is an entirely enclosed seam that looks like a normal seam from the outside and, like the flat fell seam, is sewn with 2 lines of stitching.  First, with fabrics WRONG sides together, sew a 1/4" seam.  Press open, then turn RIGHT sides together and press a fold at the seam.  Sew again 3/8" from the pressed seam to encase the raw edges.