like floydy and ed i'm a plasterer before
tiler ( or was ), dvd's can show you how to do it but you would be far better doin a course and afterwards go with a spread for the odd day here and there, a dvd can't give you the feel, it can't tell you what you've done wrong and how to correct it, etc.
one little thing that you would or should learn on the course that will make life easier for a good finish is the set up of your trowel..ie, corners, edges and curve across the blade...Mark.