If they are curvy, you should use bias strips, but if they are short or straight, using the straight grain will be fine. I cut mine around 1" and fold them in thirds as you mentioned. I iron them well (a dab of glue helps hold the flaps down) and either hand applique (not difficult - just like sewing binding only a little finer) or use a regular sewing machine stitch in matching thread on each side. You can go wider or thinner than 1".