This post shows how I work =)
First I draw a rough sketch in my sketchbook
Then I use a black fine liner to work out which parts I'm going to cut out and to define the line work.
I then scan and print a copy of the image and fix it to a back piece of paper with Repositionable Spray Adhesive and cut out the smaller parts first to keep the strength of the paper in tact.
I then cut out the bigger parts
I then remove the printed paper and photograph the black silhouette using a lightbox which ends up looking like this:
In Photoshop, I then added the black border framing the image and implemented the red lips from another photograph of red acetate previously photographed on a light box.
And that's all folks =)
(Sorry for the poor photography)