What are some things, new products can do to start marketing themselves?

The last product I built was https://jobhunt.fyi, which is a job application tracking web app for job seekers. I used one main tactic to acquire users, which was to build a free tool that integrated with my product and was valuable to my target users.

More specifically, I created a curated list of open job postings exclusively for software engineering interns (https://jobhunt.fyi/internships) and new graduates (https://jobhunt.fyi/grads). For each job listing, I had a button that said "Add to JobHunt", which would save the job to that user's account for tracking. If the user wasn't signed in, it would prompt them to sign in or sign up for an account. I shared links to these lists on Reddit, both in r/csmajors and r/cscareerquestions, since people had shared similar lists in the past and I knew they would be receptive to it. Those other lists were often just Github READMEs with poor UX, so the nice UI I provided with sorting and filtering features made for a much better experience.

Ultimately I got over 400 registered users from this strategy, from only a handful of comments and one post. If I was more proactive in sharing these lists more frequently and if I'd maintained the lists longer, I'm confident I could've gotten far more users. It was a time-consuming strategy though, as I typically spent at least an hour a day looking for new job postings to add, and eventually got too busy with college to keep maintaining it. I'm still occasionally getting new signups even though it's been more than a year since I worked on it and all the job postings are expired now.