Designing for mobile is fundamentally different from designing for desktop. The screen is smaller, the environment is noisier, and the primary input device—the human thumb—has physical limitations. Most mobile UI mistakes are entirely avoidable if you follow a few core principles.

Here is a breakdown of the essential Do's and Don'ts to ensure your mobile experience is seamless and intuitive.

1. Do: Design for Thumbs

Mobile users typically hold their devices with one hand.

  • The Principle: Primary actions should be easily reachable within the "thumb zone".
  • The UI Impact: Place critical buttons like "Buy Now" or "Next" at the bottom or center of the screen where they are easiest to tap without repositioning the hand.

2. Don’t: Crowd the Screen

On a small device, every pixel counts, but that doesn't mean you should fill them all.

  • The Principle: Avoid the urge to crowd the screen with too much information.
  • The UI Impact: Use white space aggressively. White space isn't "empty" space; it’s a tool that improves focus and makes the content digestible.

3. Do: Use Clear Visual Hierarchy

Mobile users are on the move. They don't read; they scan.

  • The Principle: Use size, color, and weight to indicate what matters most.
  • The UI Impact: A clear hierarchy ensures that even during a quick scan, the user understands the relationship between elements and knows what to do next.

4. Don’t: Hide Critical Actions

If an action is vital to the user journey, it should never be buried in a sub-menu or hidden behind an icon that requires a "guess."

  • The Principle: If it matters, make it visible.
  • The UI Impact: Avoid over-relying on "hamburger" menus for primary navigation. Keep the most important tasks front and center.

5. Do: Design for Interruptions

Mobile users get distracted easily—by notifications, phone calls, or simply walking down the street.

  • The Principle: Your UI should make it easy for users to pick up exactly where they left off.
  • The UI Impact: Use clear state indicators and save progress automatically so that a momentary distraction doesn't lead to a total loss of user effort.