Whiskers provide resistance to the razor. Thin and light whiskers provide light resistance and heavier, coarse whiskers (my curse) will provide heavier resistance, even for a super sharp blade. The trick is to figure out how much force you need to cut *your* whiskers but not irritate your face. It's a fine balancing act. And as someone else has mentioned, it also varies in different areas of your face. That's one reason why beard prep is so important -- moisture softens whiskers and reduces the pressure needed for the razor to cut through the whiskers.

As Lynn and others recommended (and not the first time) it helps to get a feel for that pressure by starting with a small area first. Then you can move on to other areas. It really does take some time to get a feel for the razor, your whiskers, and the grain of your whiskers.