Your goal is to infect as many people as possible without getting the attention of the scientists. Invest in Transmission first. It is possible to win with just the Water and Air transmissions evolved. Then, invest in Resistances, focusing in Gene Obfuscation and Natural Complexity. Have the research to move along as slowly as possible to allow enough time for your disease to destroy everything around it. As soon as the entire population is infected, evolve the first symptoms when you have at least 20 DNA points saved. One symptom will get your disease noticed, while two will start the development of a cure. Turn your disease lethal as fast as possible. Start with the Coughing and Perspiration symptoms, as they lead to lethal traits and are somewhat cheap.