Some people have done some commercial Powerwashing accounts free initially to get there foot in the door to get the account. I have never done that but I have done free samples to possibly get a job.

As for Window cleaning I have done residential and commercial accounts over the years but as of now I don't do either since my business has taken a slightly different approach which doesn't include window cleaning.

As for the advice that your asking I would do what Dan Flynn stated above because thats the approach that I use to do also.