Don't associate your products with other brands unless they perfectly mirror a lifestyle.
High-end brands are being extended across categories -- and faltering.
Brands that offer services and brands that contribute to lifestyles (such as Starbucks) can't cross over into luxury goods, and vice-versa, without thinning their brand. Can you imagine a Starbucks BMW? A Godiva Porsche? No way. There's no parity between them. But I believe in the Eddie Bauer edition of the Ford Explorer... barely.
Everyone has their own internal weights and measures when it comes to rationalizing a purchase, but I think it's fair to say this: A jacket is a jacket and is not a car. Don't overreach your category, your brand space, and what your customers will believe. It's better to cross-promote your products to another brand's audience than to badge your products incorrectly or mash your products up to try to be unique.
Don't price based on cost of goods. Price on aspirations.
People are more likely to rocket due to perceived value, not real value.
The luxury category has fragmented by budget. Audiences are asked to pay closer and closer attention to nuanced categories, with the idea that they'll always aspire to a product out of their budget.
This is known as "rocketing" in a product category, see the fantastic book Trading Up for an in-depth treatise about New Luxury or "masstige" marketing and how it differs from the old mindset about luxury goods and how the market is evolving luxury into new forms.
Don't tell a completely new story about your brand when you've already staked your ground.
If you didn't start close to the luxury space, you'll never create cachet around your product without expending a vast quantity of capital to change perception. Start a new brand if you really want to get in the game.
Don't make more! Limited quantity equals controlled demand.
Easy to understand in theory, but very hard to pull off when people start beating down your door waving fat wads of cash. Companies often cave and produce more when they should just have a plan in place as to how they can extend that demand into a new (similar) offering.
And last, but certainly not least:
Don't horse it up.
"Less is more," more or less. With clean design and smart production tactics it's relatively easy to convey an aura of luxury and exclusivity.
This is the expected first route for a designer to take with a luxury product, so don't think you have to beat a path through the weeds to engage your audience and emerge with something too novel from a branding perspective. Does it really convey the right feeling if the design is incredibly busy? Unless you're conveying some level of sophistication, your audience will have trouble understanding why they should pay 2 to 10 times the price of the competition.