I posted my website on a relevant subreddit. Initially I was really anxious, but people were really nice and supportive! I picked a very small niche sub (<2k subscribers) and rocketed to top of the day. I attribute my success to having a really casual tone and understanding my audience. With really well qualified leads it seems like >10% of my homepage impressions are turning into email subscribers! It seems like rules on self-promo can be bent if you have helpful content and you know your community.