To do any testing well requires skill. Normal testing downplays the importance of skill by focusing on the format of test documentation rather than the robustness of tests. Rapid Testing, as we describe it, highlights skill. Robust tests are very important, so we practice critical thinking and experimental design skills. We hope the articles and presentations on this site will help you work on those skills.
Normal testing is focused on functional and structural product coverage.
In other words, if the product can do X, then try X. Rapid Testing focuses on important problems. We gain an understanding of the product we're testing to the point where we can imagine what kinds of problems are more likely to happen and what problems would have more impact if they happened. Then we put most of our effort into testing for those problems. Rapid Testing is concerned with uncovering the most important information as soon as possible. Rapid Testers collect, memorize and practice using helpful heuristics.