ok, watch this guy
http://www.youtube.com/watch?v=VtQ2PsbrD4M&feature=relatedfirstly cut the blade in, the guy here does that by coming up from the side, for instance you wont get a good result if you simply press it against the side and pull across, you would have to dry of a strip first so your blade starts on a dry position if you wanted to do that, however if prefer to cut it in the way this guy does it, and you don't have a make a dry stop first that way.
Now the second point is gravity, if you imagine you have the blade vertical at the top right hand edge of the window, you must tilt the highest end forward first, this way as you pull along you push the water down, now if you did it the other way and led with the bottom end, you would be pushing the water up as you pulled the blade across causing you problems as you with get a little line of water trailing off the top because you are not pushing all the water down, as you are describing.
Now look again and see that he never holds the blade completely vertical as he pulls across and instead it is tilted in the direction he is pulling the blade.
As said above try and keep it moving and now jerk it against the sides or come to a stop when you get to the side, instead try and turn to blade a little as you come up to the edge in preparation to reverse the direction.
If you look again you will see the guy has got the blade horizontal at the exact time the edge of his blade reaches the edge of the window, thats what I am trying to describe.
watch this guy, he is starting to turn too late, not the way I would do it.
http://www.youtube.com/watch?v=jalOOJx7t9Y&feature=relatedalso the guy should be using a scrim not his wifes pink dish towel