The most important policy is "show news instead of spam".
So I will only allow banners that are (in my opinion) interesting for as many visitors as possible.
About my visitors:
All of my users are interested in room acoustics. Most of them are searching for help with small room acoustics.
I want to focus on two topics: room mode mitigation and sustainable room acoustics.
room mode mitigation
When it comes to room modes, amcoustics.com has been the top google result for years. Pretty much everyone interested in room modes visits amcoustics.com, especially my room mode calculator amroc. If you want to promote anything that helps people who try to mitigate room modes, I am pretty sure amcoustics.com is the best place to show your ad.
sustainable room acoustics
I am very interested in sustainability and want to use my website to spread the word about sustainable alternatives to petroleum-based classics.
Anything else
My focus is on the above topics. If you try to reach these target groups, you and my users will profit the most.
But those topics are by no means complete. Please write me if you think your products or services interest my users.
I picture it as a pyramid. The top is small. In relation to the total world population, only a few people are interested in room modes. But you will reach nearly everyone worldwide interested in room modes on amcoustics.com. The bottom of the pyramid is bigger, meaning that a more extensive part of the world's population is interested in the product. But there are also increasingly more sites on which you could place your ad. And the chance to bore precisely MY users increases.
I prefer ads on the top of the pyramid. Let's discuss your ideas and how the value can be the greatest for you and my visitors.