To pin baste a quilt
This part is actually really important to keep your quilt in a good shape.
Press everything well and flatten the seam allowance as much as you can.
As usual, have a backing and wadding about 2″ wider the the quilt top on all four sides. The reason you want to have them so wide is you have something properly hold onto while quilting. It is not easy to quilt at the very edge but once you have the extended edge made by those two materials, things get much much easier.
Place the top and make all the lines/seams straight as much as possible.
Place pins beside those straight lines so they can’t move much. Pins should be just off the line but not getting in a way of quilting foot while quilting. Put them parallel to the lines. That way you may not need to remove them when quilting. See the picture below.
Also pin the very edge.