No scientist, or even group of scientists, work in a vacuum. For example, the design of an experiment to discover the cure to AIDS is not realistic. Nonetheless, an experiment, or series of experiments, to determine the molecular structure of the protein coat of the HIV virus is tractable. The third step in the discovery process is to find information about the chosen topic. Well designed experiments require prior knowledge.
Library research is critical here.
For professional scientists, the background of knowledge provided by undergraduate and graduate courses that become more focused as the individual becomes closer to his or her professional goals, is also critical. The fourth step in the discovery process is the formation of a hypothesis. A hypothesis is an educated guess at the answer to the question being posited. The hypothesis must be testable and falsifiable using current technology. Note however, that proving a hypothesis false is a valuable part of the process and is considered a successful endeavor.