I like trying to fly missions with as low of a launch cost as possible. It's another dimension of optimization that is often overlooked, and the rules are different from mass optimization in some areas and the same in others. Some of the main rules of thumb: -No jet engines or ion engines. They're efficient but way too expensive -Use the Baguette fuel tank -Use liquid fueled rockets for your transfer stages and landers; use solid rockets for the launch -Don't use RCS -Try not to u