I have hired more than 25 C level officers and directors in companies ranging from startups to mature cash flowing operations. The conventional wisdom/rule of thumb, such as it is, is that as a C level you accept "half" your free market salary in cash and the rest in equity. The real rule is never work for free. Every company tries to get as much free work as possible, and every C level officer tries to get as much equity and cash as possible. When it comes time to negotiate, which should be soon, use the comp level of the other C level officers as a benchmark. If you would like to discuss this further, please feel free to get in touch.