Get your guests to promote your podcast
Think of each podcast episode's guest as a potential influencer as well, with followers and built-in audiences (even if it is just their immediate friends and family).
A speaker kit is like a toolbox of goodies that you provide to help them promote your podcast. It should include things like graphics (podcast cover, episode artwork with their name and image, or a quote), an audiogram, sample email message about their inclusion, and even pre-written social media posts or captions. This way, they can easily share your content with their networks and make it more likely that even more people will tune in to your show. You may have to remind them a few times to share, so don’t hesitate to be persistent.
Think of it this way, you're providing them with all the necessary materials to make their job as easy as possible, and that's a win-win situation. And trust me, the more effortless it is for them to promote your podcast, the more likely they are to do it.