You might consider having potential guests use a specific phrase in an inquiry through Airbnb then send them the special discount. Remember, Airbnb really wants you to only use Airbnb. They don't play with other OTAs, they don't like redirecting to your direct book website. You can find ways around it, but it won't be simple because they want everyone going through them.
You can also send previous guests special offers through Airbnb, but you can't get their contact information unless they give it to you some other way.
---> That's how I look at most guests, like cousins. And you know, some of those cousins are kooks.