to advertise your business there are many factors to consider.
a few things that will help anyone in any company even if not window cleaning.
1, be professional at all times and get a uniform (it does make a difference)
2, Your business cards should look good and be of good quality with a postal address, landline number (maybe a mobile number aswell) web address ( maybe an email address aswell)
3, never just use a mobile phone number (does not look good) having details in number 2, above has gained us 100's of extra clients over the years and have been told this hundreds of times "we used you as your card has all your details on and someone that hide things will not include these)
4, GET A WEBSITE: if you dont have one you will be missing business (they are as cheap £99, see my website as I offer this service only for window cleaners
hope this helps