I want to start a new pressure washing business with a friend and would like to know how to make quotes to our cutomers by the sq. ft. and also how to measure the work without a measuring tool.I would like to know how to give a quote for two workers instead of one that would still be fair to the customer.

Trial and error!

Sorry to sound so blunt,but,for my business at least,I found that if too many customers balked at my pricing I was probably charging too much.(or selling my service with enough conviction)
What do other companies charge for the same thing in your area?
What did you charge for work by yourself?
Who is going to be in charge of funds,and billing?
Who pays for insurance,bonding advertising?
How much profit do you need to achieve your needs and the needs of your business?
This all comes into play when you start a new business.

You might think about contacting your small business association for a simple business plan.

Good luck,
Ken

You could Quote by the hour, Experience will help to determine amount of time for a particular job. Example: if a roof takes 3 hours for 1 person. What do you need per hour?
Multiply X 3, a little for overhead and towards pressure cleaner. Say you come up with $150.00. Just quote $150.00 to clean roof. Now if you have even partner, now split the 150
and may only take an hour for 2 people. These prices are examples.
You can also charge by the hour.
In Plumbing and Electrical it may be 80-100 for the tech, and 40 for the helper. $120 per hour. Again the prices are examples. See what others are charging. You may need to raise or lower your price if no one accepts your proposal, or you work long hours like a dog and no profit. Good Luck
The licensing, insurance, and overhead will have to be split as well.