When it comes to getting into publications, the best advice I have is to read some of the articles in the publications. Either submit to publications that match your writing style and content or change your writing to fit with the publication you wish to join.
If you’re talking about the Medium owned publications like Forge and Human Parts, well, I don’t have any advice for that. My writing is not a good fit for any of those pubs. I will likely never have anything selected for those publications.
Good luck with your writing and thank you for reading and commenting!