I just started a curated newsletter about personal finance for millennials. Each issue includes 10 curated articles from various sources about investing, budgeting, paying off loans, and etc. I do not have any subscribers yet.
I would advice that you get a good social media coverage first as more people tend to look at things on Instagram, Facebook etc. It will also be good for you to advertise your newsletter on different websites. Also get a website of your own.
You can pay for an ad space on popular business magazines .