feline fanatic

No. Usually, when doing hand applique, unless you are working on the border, you are appliqueing individual blocks. so if your Unfinished block is 12 1/2" you should cut the background square 13 1/2 to 14" square. Do your applique, then once the applique is completed, square up your block to the 12 1/2".
Often what happens with hand applique (and machine applique too) is that the background fabric we are appliqueing to, tends to draw up a bit so if you cut the exact 12 1/2" before appliqueing you could end up with a block that measures 12 3/8" or 12 1/4" by the time you are done appliqueing (same often holds true for embroidery as well). So if you cut the square bigger and trim down after the applique is complete then you are assured all your completed blocks are 12 1/2" unfinished (or whatever size you happen to be working on. I just used 12" as that is such a common block size)

Kitsie

Spray starch! New trick for me with my dresden plates. Assemble the plate, spray just the back of them, put them on the background - they stay! You could spray the back of any shape.

This requires that the seam allowance of the "shape" is already turned under and pressed. I usually keep one pin an couple of inches "ahead" of where I'm stitching and move it along, but not necessary.

Silver Needle

Are you appliquéing with silk thread. That should help some.

ScrappyAZ

Ah, got it! Thanks.

Peckish

I don't pin at all. I use tiny dots of washable school glue. Once I'm done, I carefully pull the background away from the applique and trim.