Digitizing for others

For the last several years I have been digitizing for myself only. I would like to expand and have several questions.
1.How to you marked yourself as a digitizer for hire? Do you go to other shops in your area and simply ask them if they need some help?
2. How do you digitize for all the other makes of machines out there?
3.How do you keep from being "scammed" by people who say the design does not work on their machine (although it really did) and they want a refund?
4. What information should you request from the client?
5. What information should you send the client regarding stabilizer, pull comp settings, etc?
6. How to you price this service?
7. Should you send this design as email (I have heard that some browsers scramble the file) or send a floppy or CD?
8. What is the simplest way to make sure you get paid for the design?

Those are alot of questions, sorry. Thanks. John