If I were saying "five", I put would put my mouth into the position of the "f" sound. I would then move my mouth to the "v" sound. Usually what I do is alternate between the two a few times (no audible sound). There's a point where it just seems to come out on its own. Sometimes it works just as good to just put my mouth in the shape of the initial sound a few times ("f"). edit: Thanks, I tried to clarify a bit more in the original post by adding an example.