Treat users like people —
People can be emotional, reactive, irrational, impulsive, suspicious, intelligent, social, uncertain, and all very different from each other. Design for how people actually behave, use real data, and test assumptions by talking to people.
Be respectful of the user's time and attention —
Don't make something hard to find, but also only show what they absolutely need to see to get the job done. Don't trick people into doing things they don't intend, especially when it comes to sensitive information, but be honest and straightforward in your copy and interaction.
Design for as many people as possible —
Use strong contrast, make text legible and readable, avoid jargon, provide fallbacks, design for all devices AND connections, test for color blindness, use a screenreader, and always assume you can improve.
Don't leave dead ends —
Design a system, not just a set of states. Every interaction should have a beginning (empty state), middle (the key interaction), and end (clear next step). The key to engagement is a strong engagement loop.
Foster user confidence through progressive disclosure —
Whether your users is an explorer or tourist, they require time to understand your product and figure out how it can help them solve their problems. From your marketing page, through onboarding, to deeper interactions, don't bombard the user with all the information at once. Develop clear queues to understand their point in the lifecycle of use and adjust their experience to meet their needs.
Slower can be faster —
Take the time to do something right. Even in an agile environment, an MVP doesn't need to be sloppy. Start with small assumptions and build up, but make every iteration count.
When in doubt, be predictable —
Remember, you're designing for your users, not for other designers. Sometimes it makes sense to be boring. Use a common interaction instead of designing a new flow. No user will judge you. Use strong contrast instead of hanging on trends. Don't scroll jack. Leave the user thinking, "of course," instead of scratching their heads.