Go in with leverage and be ready to walk. By telling the employer you're unhappy with the compensation, you force their hand.

If they choose or are unable to increase your salary or equity, they will (correctly) assume you are not satisfied and likely will not meet your full potential. While there may be no immediate consequences, this will have long term effects on your relationship with the company.

That said, fortune favors the bold! The thread has some fine advice, good luck.