Hi Lippy, I started wfp 6wks ago, the best advice i could give you is already been said, rinse and rinse again. Also on pvc frames, be very careful around the vent covers that stick out a bit, it is really easy to brush them a bit hard and its really easy to break the ends off them, dont ask me how i know this!!
So be careful around the vents. Also on the 1st clean, wash the frames of all the windows 1st, then go back and wash the glass, this will let the frames stop dripping any dirty water onto the clean glass.
Lastly, be careful about front doors, a lot of letter boxes leak and so I am very cautious and use less water and often use trad for the front door.
Tim