I check my machine tension every time before I start quilting. I usually will just grab a strip of fabric, set it on top of the excess batting & backing along the edge of my quilt & stitch a tiny sample just to ensure that tension is correct for thread & presser foot. If I feel I need more, then I'll grab some scrap fabric & batting and make a small quilt sandwich (up to 1/2 yard). Should be the same material, batting & thread as your quilt. I don't pin practice sandwiches because they're so small.
If puckering is all over, it's probably due to layering issues. For the bottom layer, lay it out flat & then use tape to floor or T-pins to carpet to just gently pull it smooth -- not taught. Then just lay the batting & quilt top over the backing & gently smooth with your hands before basting. If any layer is pulled taught, you will get puckers.
If puckering is in the center of quilt top, Pin from the center out. I pin by quadrants from center out & then go in order by diagonal quadrants (upper left, bottom right; upper right, bottom left). You want to quilt in the same fashion so you push any puckers out to the edge of the quilt rather than trapping them in the middle.
If your puckering is just along the outside edges of your quilt, you need to thread baste the edges down. I grab whatever junky thread I have & any hand sewing needle and just run a quick basting stitch within 1/4" from the edge of the quilt. Some people leave that in because it's hidden by the binding, but I always pull mine out because it barely takes any time to unsew basting stitches.