In the customer's shoes
I recently read Jason Cohen's Uncommon Interview with Peldi from Balsamiq Studios and found this quote particularly intriguing:
I always try to put myself in a potential customer’s shoes. The qualities I look for in a software vendor are honesty, attention to detail, focus on usability and outstanding customer service, so that’s what I want to offer at Balsamiq.
It's all about delivering the qualities you yourself would seek out, if you should purchase the product that you sell.