I typically try to use a dimension within the quilt... If its a log cabin and I cut strips 1.5 wide then thats the width I use for the border. Or I use varied width... but try to keep the scale of the blocks . I have used all kinds of scrap strips cut lenghtwise and cross wise ... I just starch the daylights out of the fabric before cutting or sewing, and have not ever used a foundation. I do stop and stay stitch both sides of the border about every 2 feet or so ... working with long pieced sections .. the weight will start to pull on the stitches and the seams can seperate.