What actually affects whether a site works.
CLARITY OVER CLEVERNESS
A visitor should understand what the site offers without effort. Clever design that requires interpretation loses people.
HIERARCHY
The most important thing should be the most prominent. If everything is emphasised, nothing is.
CONSISTENCY
The same fonts, colours and layout patterns throughout. Inconsistency reads as unfinished.
WHITESPACE
Room around elements makes them readable. Cramming more in makes a page harder to use, not more informative.
CONTRAST
Text must be readable: dark on light, or light on dark, with enough difference. Grey text on a light grey background is a common and serious mistake.
MOBILE FIRST
Design for a phone screen, then adapt upward. Most visitors are on phones.
SPEED
A beautiful site nobody waits for is a failure.
WHAT DOES NOT MATTER MUCH
Sliders, animations, parallax effects, elaborate transitions. They add weight and rarely help anyone.
THE TEST
Can a visitor find what they need without thinking about the design at all? That is what good design does.