Remember to wipe the rubber blade after each squeegee stroke with a lint free cloth. If you place a wet squeegee on the glass it will put a blade mark. Do not worry, with practice you will be able to wipe the blade quickly.
You must always wipe the edges of the window pane to get rid of the water marks and spots. When you are done with the squeegee, just wipe the window edge with a lint free cloth.