Another problem you’re going to see when you test is that sometimes what users are looking for is on the page, but they’re just not seeing it. Thus, you need to either (a) reduce the overall noise on the page, or (b) turn up the volume on the things they need to see so they “pop” out of the visual hierarchy more.
Don’t make me think
Being an expert in online usability Krug gathered his experience in a wonderful book. This summary of key thoughts will help you to remember most important principles and laws.