The trick is to sell the ads yourself directly to marketers who want to reach your audience without networks or middlemen.
Linus Tech Tips has merchandise in part because it means that their single biggest income source is not a sponsor.
Swag might not be your thing, but the message I got was pretty clear: make sure you can always walk away from any advertiser, either because they're a small part of your revenue, or you're living below your means.
I think people don't give readers enough credit. They can tell if you start compromise your coverage for an advertiser. And you'll never be able to recruit and retain quality journalists if they get even a whiff that they won't be editorially independent.
If you refer 10 other board members we'll send you a shirt :)
Kinda like how magazines work. Because really a newsletter is just a digital magazine.