Ask HN: Negotiating with an early startup

So I've been offered a position at a new startup with good funding, good plan and a mvp already. I'd be coming on as the first employee to create a more robust back-end and start expanding the product.

I already have the answers for:

Is a start-up for me? Does this start-up look like it has a future?

And now I'm at, what do I ask for at the negotiating table?

I've been offered a salary about 12% less than my current, but better benefits, better working environment and room for growth.

I don't really know what protocol on asking for equity is or if I should. It wasn't brought up in the original offer so I'm not really sure on it.

Anyone have any more experience in this area?

Thanks!