You are establishing a business and therefore must approach it as such.
Have diagrams or pictures ready of the designs you are using up to date in a large ring bound notebook.
Make a listing of all you want to discuss with your 'clients' and put it in a written format. This will hopefully prevent customer complaints. You will be able to show clients what you discussed as far as design, thread, etc. Also have room for any special comments on what is desired.
It is nice to have receipts for customers so you can prove they paid and when you said you would have the quilting done by. Also the receipt numbers will help you keep track of incoming quilts. This means you will need to keep some sort of a record book.
If a customer makes any changes then get it in writing before doing it!!!
Make it fun and keep it affordable.
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