Dieter Rams's design principles
Dieter Rams' 10 Principles of Good Design are a good place to start in a broad sense.
“Everything interacts with, and is dependent on, other things. We must think more thoroughly about what we are doing, how we are doing it and why we are doing it.” -Dieter Rams in Rams, 2018
Rams' influence is remarkable and his principles are considered design dogma. Anyone who went to a product design school has studied them already, but it never hurts to brush up on fundamentals.
Good design…
is innovative. Staying close to innovative technology is often thought of first. But innovation happens when someone introduces a new method or idea. The technology needed to make an electric car was available for 100 years before they were presented in innovative ways by Toyota and Tesla.
makes a product useful. Perhaps the greatest differentiator between art and design. Art has potential to be useful, for design it is mandatory.
is aesthetic. How something looks can change how we feel or how it is understood. A design should appeal to the senses of the people it's designed for.
makes a product understandable. If a product is not intuitive or familiar, people may give up on it. From a design and business standpoint, there is very little that is more challenging than to change user behavior.
is unobtrusive. A user's attempt to achieve something should not be hindered. Don't design what you want, make a tool for others.
is honest. It should communicate, "what you see is what you get." Dishonest design is manipulative and deceptive. For example, before 1998, Pyrex was made of borosilicate glass. This is much stronger and resistant to extreme shifts in temperature than the soda lime glass they quietly switched to.
is long-lasting. If a product is fashionable, it risks becoming antiquated. Protect the environment the user lives in. Protect the relationship between the product and the user.
is thorough down to the last detail. All design decisions are made with intention and never over personal opinion. Even the smallest details should be scrutinized.
is environmentally friendly. One thing Dieter hates the most is the excessive amount of thoughtlessness in today's designs.
is as little design as possible. This is a core concept for anyone creating anything useful. Simplify. Simplify. Simplify.
Different principles can be used for different needs. There can be variations to meet the demands of the scenarios you design for. Universal Design Principles are different because they were defined to guide designers to develop solutions that can be used by people of any age or ability.
Principles are a shared direction. The useful thing about design principles isn't to prevent you from following bad ideas. It's to help you say no to good ideas so that you can focus on great ones.