About what angle are you holding the blade? Try to guesstimate the distance from the spine to you skin, angles are too easy to misjudge. If I had to guess I'd say probably a combination of too steep an angle and too much pressure. High angle makes it drag more and the more it drags the easier it is to apply too much pressure. Maybe try a shallower angle and shorter strokes, swiping about an inch or less at a time.

Like Hirlau said just keep at it. Takes a while to get the feel & muscle memory needed for consistently good shaves.


Edit: there's a difference between drag & pressure, but the one can easily lead to the other.