I personally avoid using the tack strips myself. I like the hand stitched look, it takes longer but is easier to control. I actually pin the material and hand crease it so I have a guide while I'm stitching to help prevent any puckers. Try to follow the weave of the material while stitching by following a thread in the material and placing you needle in the same spot in the weave you'll prevent some of those puckers as well as make sure when blind stitching you have the in and out point of the two fabrics at the same spot. Too short and you'll get pucker too long and you'll see the thread, hope that makes sense.
Clay
Clay