I’m a doctor negotiating with a company about my role as an advisor vs potentially CMO.. I am completely new to start ups what should I know/discuss? I will not promote

I got offered around 0.5% in advisory shares vesting over 3 years, with room for additional salary/equity with continued growth. But the work I’d do seems pretty essential and key to the company so that percentage seems awfully small. But it also seems to be on par with what I’m reading so my expectations are definitely off so that’s why I’m here. What should I know/discuss?