How does the customer choose the winning quote?
It is up to the customer. Your portfolio, bid, pitch and conditions are shown to the customer and may all affect the outcome. The number of quotes you are competing with may also affect whether or not you win. Customers may have different needs. A customer looking to save money may select a cheaper or the cheapest quote. A customer looking to find a designer they can use again and again may be looking for the highest quality designer, with the best portfolio and communication skills.