If you're not familiar with Quora, it is a question-and-answer platform where users can ask questions on any topic and get answers from other users who know about that particular topic.
No matter what topic your site covers, you can use Quora to find relevant questions and long-tail keyword ideas.
To find relevant questions, you can directly search on Quora with your seed keyword (topic) and note down the questions you think are relevant to your topic.
But Quora search is not very effective. So simply type in Google site:quora.com [insert your topic], and you will get hundreds of questions that you can target.
Click on any of the questions, and then on Quora, look for the answers with the most upvotes.
You can also look for more relevant questions when you scroll down to the end of each page.
Now you can use the questions as standalone articles where it makes sense, or use the questions as FAQs in your blog posts to increase the topical relevancy.
Finally, you don't have to limit this to Quora only; you can also try Reddit and industry-specific forums to find highly relevant long-tail keywords.