Make sure you always plow in the same direction. It sounds simple but I've seen many a novice farmer try plowing in both directions and it just doesn't work like that! Your 1st run needs to be straight as possible. Back up and put the tractor's wheels in the furrow, then when you plow this 2nd row the sod will fall into the first furrow you made. A one bottom plow like you have should be fairly easy. Also you should disc first, wait a few days then plow, wait a few days then disc again. By discing first it breaks up the roots and makes a much better seedbed.