Techniques on finding new users from forums?

Basic:

• Plug your product in your bio and/or signature.

• Plug your product on any threads which are meant for self promo. Some subreddits have this.

• PM moderators and see if they can add your product to the forum / subreddit wiki.

Advanced:

• Jump into conversation threads and add value - be helpful, even when it isn't related to your product. When it is related, do a mini plug for your product if it is allowed. Sometimes, I have also mentioned alternatives to my product to build trust. The focus on your post should not be your product, it should be to help the OP, who should be your target customer.

• Start conversations about the problem you are solving. Don't mention your product; just provide the opportunity for members to speak about their problems. Hopefully they are passionate enough about the problem to write / talk about it. Then, try PMing potential target customers based on their responses. I have found a few early passionate users this way.

Like @dhruvg mentioned, the most important thing is to add value - don't plug your product unless its relevant. Try and find communities where it is (you don't have to be a long time contributor, just someone who adds value).