4. Set post-search filters. After your keyword suggestion fetch is completed — which might take a while if you input a lot of seed keywords — you need to filter your list. You can: filter out keywords that don’t include buyer modifiers like “best”, “buy”, “purchase”, “discount”, “review” (it’s possible to input one or more words in the filter field at the same time: just separate the words with a comma); add a minimum and maximum amount of LMS; set a minimum amount in “Suggested Bid”; and check for only high “Advertiser Competition” keywords.
Google prefers to not share long tail searches in this tool – because the tool is designed for Google Adwords advertisers. If advertisers bid on those long tails – they would have less competition and therefore pay less for the Adword, and therefore Google would make less money e.g. bidding on the term weight loss for girls under 18 is cheaper than weight loss.
Repeat this exercise for as many topic buckets as you have. And remember, if you're having trouble coming up with relevant search terms, you can always head on over to your employees on the front lines -- like Sales or Services -- and ask them what types of terms their prospects and customers use, or common questions they have. Those are often great starting points for keyword research.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website. In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC). I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.