3. Set your pre-search filters. Depending on whether you are looking for a new niche to build a site around or trying to find keywords to target on your already existing website, the minimum amount of local monthly searches (LMS) you set might vary. For new niches my LMS criteria is 1,500-5,000 searches, for posts anything from 10-800 is fine. Also, depending on one of these goals you can add a lower or higher number of words in the respective filter: for new niches 3 (or, at times, 2) words minimum, for new posts from 3 or 4 words up.
This is slightly more complicated than it used to be, because you have to actually create a live AdWords Campaign as part of the process! This puts many people off, as it looks as if you have to actually advertise in order to use the tool. You don’t — you can just setup the campaign and then pause it before it runs so you don’t have to spend a penny.
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.