Have you ever considered the differences between best practices and design principles? You might wonder why it should matter. “After all,” you may reason, “Whatever you call them, the point is to have rules and parameters in order to make the product better, and deliver a better user experience. What’s in a name? Why split hairs?”

Well, as it turns out -- it matters quite a bit. Because if you don’t know the difference between the two concepts, and act accordingly, you’re in danger of ending up with a slick and easy-to-use product that doesn’t say a thing about who you are and how your product is unique. And with no brand differentiation, how can you be competitive? Why would anyone see the reason to choose your product over all the others that seem to be just like it?

Not convinced? Take the case of Lyft. In December 2015, Frank Yoo, Lyft's director of product design, created what he thought were design principles to guide the company's app redesign:

• Nail the Basics: Clear Choice and Context
• Build Confidence: Consistency and Transparency
• Be Unique: Ownable and Delightful

The only problem is, these aren’t design principles. They’re best practices. And using them as the organizing principle for the app design contributed to a user friendly app .. that was nearly a carbon copy of their biggest competitor, Uber. If Lyft was looking to distinguish itself as a clear alternative to Uber at that time, they failed.

But you can easily avoid this trap, because once you know what to look for it’s not difficult to tell the difference. Best practices are, in a word, universal. They’re widely accepted standards of quality and could apply across the board anywhere, anytime. And in that sense they are generic, and won’t distinguish your product from the competition.

Design principles, on the other hand, are very specific. They are unique to your product and your vision, and they should serve to differentiate you and convey your unique value to users.

To sift through your own design principles and make sure there aren’t any best practices lurking among them, it’s helpful to ask a series of questions:

• Is this broad or specific?
• Could this apply to multiple projects/mediums/products?
• Is this universally true?
• Could there be situations where this would not be desirable?
• Does this set us apart?
• Does everyone strive for this?

Using this criteria, Yoo’s “principles” are clearly best practices. “Nail the Basics: Clear Choice and Context,” for example, is broad, could apply to any project, is universally true, always desirable, does not set them apart, and is something just about every designer strives for.

Compare this with one of Code Academy’s design principles: 

One Column — Whenever possible, we have constrained our entire content to a single-column layout. This helped us focus on the core purpose of the page, while also giving us more control over our narrative. A one column layout was also easier to implement within our first responsive design system, by minimizing variation between different screens and form factors, such as mobile and tablet.

This is incredibly specific, could not apply to multiple projects, is not universally true, could be undesirable in other circumstances, sets Code Academy apart, and is not something that every designer strives to do. Design principle? Check!

Prioritizing Your Best Practices

Once you’ve checked to make sure your design principles aren’t actually best practices in disguise, you should still prioritize your best practices on a per-project basis After all, there are literally hundreds of best practices to potentially focus on.

But, you might protest, if best practices are so universal, why bother prioritizing when good designers should automatically know which ones to use in a given situation? While that’s a fair point, keep in mind that while you, as a senior designer, have likely internalized scores of best practices and intuitively know which ones to draw from in any scenario, your junior designers probably aren’t quite there yet.

Plus, it’s always good practice to make certain that everyone is on the same page. Marty Cagan wrote that, “Good teams have a compelling product vision that they pursue with a missionary-like passion. Bad teams are mercenaries,” and this applies here as well. Getting everyone aligned and prioritizing your best practices can help hone your vision and free you up to pursue it with passion.

That said, with literally hundreds of best practices, how can you effectively and efficiently choose and prioritize which ones matter most for a given project?

First, it’s a good idea to remind everyone about the project’s salient points:

• What is the product’s purpose?
• What need does it fill?
• What are the user’s goals in using this product?

With those answers in mind, sort your best practices using the Moscow Method. Which of your core best practices are:

• Must Haves?
• Should Haves?
• Could Haves?
• Won’t Haves?

Once you’ve sorted your best practices into these categories, you’ll have a clear idea about which ones to prioritize for your project. As Kingshuk Dak wrote in Strategy vs Design Thinking, “Capability — the realm of what you can do — is not the problem; the question is, of all the things you can do, which ones should you do?”

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