Welcome Dan. I still have a car valeting business running after being in that business for over 15 years -
here. I tried out window cleaning towards the end of last year as a form of reliable regular income when the recession was at it's worst here and very few where spending on valeting. I was suprised how easy (well, fairly easy) I built up a small round by canvassing door to door and even though the valeting has picked up slightly I now run both businesses with my sights set on moving into wfp window cleaning full time when possible.
The reliable regular income is far easier to build in window cleaning that valeting.
Best advice I think I think I could give (being pretty much a window cleaning newbie) is - safety first. I came close to a fall one day and it scared the life outa me. If you're worried about a particular climb position, trust your instinct and don't do it.
And good luck with the business.