1. Involve code early

   Web interfaces are made of code. If you’re not working with code, you’re not working on the interface. That’s not to say there’s anything wrong with sketching or paper prototyping — in fact, I recommend paper prototyping in my book on inclusive design. Just work with code as soon as you can, and think about code even before that. Maintain a pattern library of coded solutions and omit any solutions that don’t adhere to basic accessibility guidelines.
   

2. Respect conventions

   Your content should be fresh, inventive, radical. Your interface shouldn’t. Adopt accepted conventions in the appearance, placement and coding of interface elements. Users aren’t there to experience interface design; they’re there to use an interface. In other words: stop showing off (unless, of course, the brief is to experiment with new paradigms in interface design, for an audience of interface design researchers).
   

3. Don’t be exact

   “Perfection is the enemy of good”. But the pursuit of perfection isn’t just to be avoided because nothing ever gets finished. Exacting design also makes things inflexible and brittle. If your design depends on elements retaining precise coordinates, they’ll break easily when your users start adjusting font settings or zooming. Choose not to position elements exactly or give them fixed, “magic number” dimensions. Make less decisions in the interface so your users can make more decisions for it.
   

4. Enforce simplicity

   The virtue of simplicity is difficult to overestimate. The simpler an interface is, the easier it is to use for all kinds of users. Simpler interfaces require less code to make too, so there’s an obvious performance advantage. There are many design decisions that require user research, but keeping things simple is always the right thing to do. Not simplified or simple-seeming or simplistic, but simple.
   
   Do a little and do it well, for as many people as you can.