Design Principles - a guide

What are they?

Design principles are a set of loose rules that I design to, specific to the project I’m working on. For example:

  • Show don’t tell
  • Don’t break the main experience to cater for edge cases
  • Enhance conversations, don’t replace them

There were also some principles published on the Government Digital Service a few years back.

Why use them?

They help make design decisions. Often two solutions to a problem will present themselves. You can use the design principles to determine which solution is the most appropriate. Most importantly they help explain and defend design rationale.

Getting a solid set of principles agreed and signed off by the client gives them a great framework to critique the designs against. Critique becomes less about what the client likes and more about what’s appropriate to the principles you’ve set out.

You’ll never completely get rid of feedback based on opinions, but design principles definitely help.

How to make them

Writing good design principles is actually quite hard, but worth it. It takes a bit of discussion and a lot of re-writing to get those few statements right.

Design principles should be created once you’ve got all your research and before you start designing, wireframing or even sketching.

A good place to start is look at any user research that you have and answer the questions: What should we do for the user? What should we not do for the user? Once you’ve listed the answers out your design principles tend to present themselves.

If you were not the person who conducted any research it’s always a good idea to run your principles past whoever did conduct user research to see if the principles you wrote are inline with what they experienced first hand talking to users.

Get the principles signed off by the client so that they are aware of them and have agreed to them.

That way, if there is a debate over a design or they provide amends that may not be appropriate, you can refer back to the principles and ask if these ideas support this principle or go against it.

What makes a good design principle?

A good design principle should fundamentally allow you to make a design decision. When you write a principle ask yourself if it will help you make a decision, if not, ditch it. I’ve come up with a few rules for how to make design principles.

I’ll be honest I’ve looked back over old projects and I’ve created principles that break some of these rules, but it's a good set to aim for...

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1. Ground them in user or business needs

X Use flat design

√ Reassure users that they have supplied the right information

√ Re-use elements from other services where appropriate to speed up build

Design principles should not be based on trends - but on what is important to the user or the business.

2. Don’t sit on the fence (they need to help you make a decision)

X We should consider performance

√ Performance is more important than interactivity

3. Practical and actionable, not aspirational (no fluff)

X Be the market leading website

√  Allow our expertise and experience to shine through

4. They are not requirements

X Allow users to filter data

√ Allow the user to see data the way they want it

If you write a design principle that is just a solution to a problem, that’s only going to help design that one thing. Think about what user need that solution is trying to fulfil and base your principle around that.

5. Not too obvious

X Easy to use

√ Don’t overwhelm the user with details

Think about the opposite of your design principle, would anybody choose that? Would anybody have a principle of difficult to use? Whereas the opposite of don’t overwhelm me with data would be: "show me all the details" - which could be appropriate for a different project.

6. Quotable

X Don’t give people too much information at once causing them to get confused and overwhelmed

√ Don’t overwhelm users with details, you want the core principle to be memorable.

You’ll know the principles are working when other team members and stakeholders quote them to each other in meetings, and keeping them snappy and quotable really helps with that.

7. Try and create one or two that differentiate this product from competitors

This is a tricky rule to follow, but if you can manage it, it will help the final product be different in a way that is meaningful to users.

For example, I was working on a project for a travel website that specialised in school trips. Teachers would come to the site to pick a holiday, book it, then sell individual places to students. The website contained a lot of information about the educational value of the trip and what key stages it was relevant too. The travel company felt this was important, as did their competitors as they all had similar information on their sites.

However, when we conducted research with teachers we discovered that they didn’t care about educational information. They were teachers. The fact that a trip up a mountain is good for geography students was obvious to them.

What they were concerned with was selling places on the trip, and they couldn’t sell the trip to students with educational value. They needed to sell based on the amazing time that the students would have.

So we created the principle: Focus on experience, not educational value.

This guided how we chose copy, images, how the layout of product pages were designed and more. It also meant we were doing things differently from the competition.

Some things to remember...

Design principles are not the gospel truth. What may be right for one project may not be right for others.

You may also need to include principles that may seem obvious to you as a UXer. A principle I included on one project was: design to match user needs, not our organisational structure. This may seem obvious but having this statement signed off by the client helped steer them away from falling back into that bad habit as we got further into the project.

Don’t make too many, 5 or 6 should be enough but you shouldn’t omit a principle just because you’ve already got 6 of them. However I would say when you get close to 10 they will become less effective as there will be more to remember and more to adhere to.

Design principles are immensely valuable during design projects. Although they take some time to write, you’ll get better at coming up with them over time. It you don’t agree with any of the rules I set out, or have some rules of you own I’d love to hear them.

Steve has spent the last 8 years at cxpartners trying to write the perfect biography for the website. Has a medium cat