I know that it is very difficult to gauge a candidate's attitude / work ethics from the start. What are the most important things you look for a candidate that will be fit for a startup software company?
Phase 1: do they have integrity, intelligence, maturity (can they handle stress and setbacks)?
Phase 2: are they positive, energize others, courage to make tough decisions, and get things done?
Phase 3: why did they leave their last job? and the job before that? Make reference calls, and probe.
Jack Welch - CEO of GE - noted as manager of the century by Forbes (I believe, maybe Fortune)