What I did was cut straight up the middle, add binding to the sleeves and center fronts, add buttons and buttonholes, and then add a gathered piece to the neckline. Today I have a tutorial for the binding.
Sew at 1/4". (I sewed at 1/8", but it's much easier at 1/4"!) Be careful not to stretch or pull the sweater as you sew.
Trim the edge to an 1/8".