Ask HN: People with more than 5k newsletter subscribers, how you get sponsors?

Greetings Readers

I have a newsletter at around 8k subs, around showbiz.

I am planning to implement sponsorship spaces in my newsletters, I have a open rate of around 20%-30%, and I was wondering if you had to sponsor a newsletter or perhaps if you have your own newsletter, how do you set your prices?

I am aware of existing platforms like paved, kit etc, but how can I directly just approach potential people for sponsorship and how do I rate them?

Thanks for your time!

KV