My anecdotal experience agrees that blog posts with promotions are better than "here's my product" , on average. Though you can just do both.
I've front paged Hacker News a few times and I've recently had a lot of success promoting a product on Reddit.
Often times I see boostrappers hype up Twitter as a marketing channel and lament that Reddit / Hacker News is impossible since it's a lottery to get upvotes, mods take stuff down, and users are hostile to promotion. While there's some truth to that, I think these people don't "get" these upvote platforms.
If you drive-by and drop off a link to a product, it'll probably get lost. If you write something really interesting then leave a promotional message at the end, it'll probably work fine. On sites like Reddit specifically, it's better to put more content in the post rather than link out (sucks for your site's SEO but much more likely to get upvoted).
There's definitely some luck to Hacker News but cream also does tend to rise to the top and you're allowed to re-submit.
It's annoying that there's a subset of HN and Reddit that think that anyone trying to make a dime on the internet is somehow sub-human, but they are a minority . I followed my strategy with a a Reddit post recently and the person complaining about my promotion of a paid product at the end got 13 downvotes ( https://www.reddit.com/r/poker/comments/13wt05l/lsg_hanks_ri... ) . Because people liked the content so will forgive a promotion if there's some value add.
Ultimately people value being entertained and value learning useful information. So if you can do one of those two things, they will probably forgive a product shoutout.
Funny thing is I really struggle with Twitter and have the "tweeting into a void" problem but Reddit / HN seem to come more naturally to me. Though I'm guessing the secret is another variation of "be more entertaining or more informative".
But you can also try different stuff, you can do a Show HN and a blog post.
There's one last really important thing I don't see mention on Max Woolf's Hacker News undocumented. If you submit your own blog too many times without enough upvotes, you will get auto-flagged. So make sure you submit some random other stuff you find interesting to please the algorithm gods. But that goes back to "act like a regular member of the community and the community will forgive some self-promotion".