How to go from 100 to 1000 newsletter subscribers

Hi fellow hackers,

I started a newsletter that curates the best product management content. I share articles that can be read in 15-20 minutes thus ensuring a daily healthy habit. I started 1.5 months ago and reached 100 subscribers by posting on relevant slack and reddit groups.

I am seeing open rates of ~30-35% constantly. I want to grow my subscriber base to 1000 over the next year and also start developing my twitter audience (it's at 20 right now).

Would love to get some tips on how to grow my newsletter from this fantastic community!!

My newsletter: dailypm.substack.com
Twitter: https://twitter.com/rsikka14