Avoiding traps with self-publishing firms

Helen Sedwick lists seven questions that potential self-publishing authors should ask when evaluating offers from a self-publishing service company (SPSC). For example, she writes, how much will you be paying for copies you buy yourself to give away or for resale? "The author price should be the actual printing costs plus a reasonable markup (15-20%) and not a discount from the retail price. Why pay more because the SPSC sets the retail price at $20 instead of $10?"