In the last month or so, I've had the good fortune of witnessing high level employees quit from 2 startup companies. In both cases, the employees were well meaning honest folk who did a poor job of communicating to the management of the start up.
if you find yourself in the position of management at a startup (or for that matter any company) and wanting to quit, I would encourage you to notify the management as soon as possible that you are thinking about leaving the company and some of the life factors that are making you consider leaving.
This early warning step is the one that people screw up most -- and often has the most negative effects on the entire process. It often makes employers feel burned when they don't have fair warning or opportunity to correct bad employment circumstances. Why is this so important? Two reasons: first, because startups need to be able to plan for effective transition and second, managers want to feel like they have an opportunity to communicate or respond to market dynamics with a counter offer. Without adequate warning, managers end up feeling burned and can take defensive or punitive actions in response. These only aggravate bad communication and bad feeling between employee and mangement left at the company.