Ok so DH and I have been discussing for a while starting up an after hours cleaning service.

It would be cleaning of buisness/offices that we would be looking at as we are around quite a few industrial estates that we would drop flyers/advertise etc.

My main question though is quoting... I have a rough idea of how much we would charge however is there a guideline that I should be working to?
Do cleaners usually charge in an hourly rate or by square metre or just look and quote?
Any ideas that could help me would be great.