We did this with all our advisors. X base shares that vest with time. and Y additional shares for every intro to a customer. To be clear, they earned the Y additional shares if the prospect signed an LOI. We did not add further incentives by sales process, as we figured the rest depended on us / our value, pitch, etc. and would be unfair to hold the advisor responsible.
It's best to do fewer shares vesting over less time, so it forces you to re-eval if things are working.
If they are helping to navigate the org and it requires some time from them, you can also propose a success fee in %$.
X dollars or equity for every referral and Y% if it results in a sale. You definitely want to weight it heavily towards Y. That gives them a strong incentive to not only help you navigate the org with introductions, but also with coaching. And by Y% I mean a commission on the sale TCV. For example, if your deals are 6 figures, you would propose 3-5% success fee.