Step 5: The cut's
The technique is basic; when cutting apply moderate pressure and instead of trying to only turn your hand (like using a pencil) turn the blank as well. Try to make long stoke cuts trying to avoid stopping or lifting the knife as this creates points you'll need to re-cut during the removal of the pieces.
Note: I've seen quite a few stencil tutorials that tell the beginner to use card stock or paper, and it's a great idea for a one time use (maybe even a couple times). Though the nice thing about stencil blanks is that they are resistant to most thinners and they can be used hundreds of times over and over again. As an added bonus the sturdiness of the blank doesn't lift off the project as easily from the paint blast force (creating that cloudy effect around the edges) that you will get from card stock and wax paper.