I have all the card stock cut (still need to score card bases), sentiments are stamped and punched, ribbon cut.. I just need to adhere the stickers to the white layer.. and I figured out a trick earlier when doing them so that they go on straight every time (description and photo below).
I use Stampin' UP! grid paper and I had a scrap piece of black card stock that is 4" wide. I lay it down on the grid paper so that I can see where the center is by the measurements on the grid paper, then I lay the white layer on it. I take the backing off a small part of the sticker and start it on the white layer about 1/8" from the edge (in this picture I was more like 1/4" and had to trim a small amount from the bottom) .. then smooth it down. Do this slowly and smooth the sticker out. If you are off by a little bit on one side, just trim it with a paper trimmer, it won't be noticed when you put the card together.