My advice would be to make use of pre-launch platforms such as <a href="https://microlaunch.net" rel="nofollow">https://microlaunch.net</a> or product hunt and other organic ways to gain traffic. Meanwhile, make sure your funnels converts, then think about Ads later on.
There is no solution that fits all.
Depends of your target audience and where they operate.<p>Audience is on Twitter/X ? Build in public and post regularly about your work.
Audience is on facebook ? Targeted Ads may work for you
Audience is a set of professionals ? Target forum or places they go<p>Disclaimer: I'm not an expert in marketing either :)
Reddit is a really great way right now, due to the boost to Reddits rankings on Google you can find old Reddit threads that still allow comments in the top 5 on Google with very high traffic keywords.
Talking to potential customers one at a time is the simplest thing that might work. And it will be work. Hard work. If you don't want that hard work, don't have customers.<p>Talking to customers one at a time is hard to scale and it is easy to scale zero customers. This mostly makes solutions that scale attractive when starting out. Scaling when you have many customers is hard work. Harder work than talking to customers one at a time.<p>Good luck.