BATTing, butt edges and overcast with either a wide zigzag or an overcasting stitch. No ridges.
For set in seams, I place a pencil mark at the 1/4" seam intersection. I start sewing from the inside point to the outside, this way there is not a chance of ending up with a tuck. Do one side, finger press, then you should be able to just line up the other side, matching the previously sewn seam and pencil mark, aligning the edges of the fabric, and again start sewing from that intersection point to the outside. I take 2 or 3 stitches in place, ( set the machine stitch length to 0 ) exactly in the intersection, placing the needle carefully down into the intersection, take the stitches and then begin sewing at regular stitch length.