How to Use Sponsorship Slots to Promote Your Own Products

I've observed a bunch of these kind of independent media businesses, but I've never actually sold sponsorship slots like this. How do you assess the value of using that real estate to just promote your own products versus other people's products? Yeah, in a newsletter where I wouldn't already do that, that would probably be a good idea. But I feel just as much as I don't want to oversaturate people with ads in general, I don't wants to Oversaturate them with just my stuff.