I'm just learning this also...I was told to use Heat and Bond lightweight. So far it sticks fine. I'm still practicing my machine blanket stitch using different threads. I took a class and the instructor used the invisible thread but I wanted to try the pretty threads such as either Mettler or Sulky, etc. Haven't decided which I like yet, but the Heat and Bond seems to work fine. You can buy it most anywhere that sells fabric. I tried both cutting the center away and leaving the whole piece and ironing it to foundation. Some of those seemed a little stiff. Probably depends on your fabric. Looks nice when stitched down though.