Don't Make Me Think: A Common Sense Approach to Web Usability, 2nd Edition

Caroline Jarrett has an entire chapter about it (“Making Questions Easy to Answer”) in her book Forms that Work: Designing Web Forms for Usability.

Your objective should always be to eliminate instructions entirely by making everything self-explanatory, or as close to it as possible. When instructions are absolutely necessary, cut them back to the bare minimum.

If you’re not going to use an existing Web convention, you need to be sure that what you’re replacing it with either (a) is so clear and self-explanatory that there’s no learning curve—so it’s as good as the convention, or (b) adds so much value that it’s worth a small learning curve.

It doesn’t matter how many times I have to click, as long as each click is a mindless, unambiguous choice. —KRUG’S SECOND LAW OF USABILITY