One type of content that can be done easily with long-tail keywords are FAQ posts. Creating these can be done by compiling the questions that people search for using a tool like Ubersuggest. I usually end up with at least ten keywords that have between 10-50 searches per month and very little competition. An FAQ section can also be added to the end of a long-form piece to capture additional traffic.
Creating FAQ posts have an added benefit of appearing in the answer box when people make a search, which improves the CTR.
Another strategy that has been working for me to focus on long-tail keywords that have commercial intent. Words such as "buy, special, deal, review, shipping" etc. all have a high ROI - even if the search volume is minimal compared to the head term.
I hope someone finds this useful.