Pin basting your quilt is an easy way of holding the three layers of your quilt together, but it does mean that you have to keep stopping sewing when you are quilting to remove the pins. Otherwise you risk breaking the needle of your sewing machine: I know because I have doneit!
A quilting pin is different from an ordinary safety pin because it has the curved edge tocope with the thickness of several layers of abric without puckering the fabric.
After layering your quilt, begin in the middle of the quilt with the first pin and then gradually work outwards, smoothing each time before you insert the quilting pin.
Ideally, try and put a pin in about every 4″ to give a good hold to the layers of fabric, but avoid any part where the seam allowances look bulky because you could risk either bending the pin or making a hole in the fabric as you try to put the pin through too many layers of fabric.
Pin basting quilts is quick and simple to do. It has the advantage that as you quilt you can smooth the fabric further if it has begun to wrinkle slightly with the quilting. This is not an easy option with thread basting. The disadvantage of pin basting is having to stop and remove the pins as you quilt.