You need to take the subject of your niche and be a bit imaginative
. Narrow down your niche because if it's too broad the competition will be huge. When you enter your keyword, lots of related suggestions will appear. Sort them in order of search volume then don't be too ambitious, choose 1000 to 5000 searches then type the phrase into Google enclosed in quote marks. If the number of pages featuring that phrase is less than 10,000 then you have a chance of ranking for that long tail keyword; the fewer competing pages, the better. Write a 200 to 400 word post to your website or blog featuring your chosen keyphrase and you should see the traffic roll in.