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.
I just have the free version right now so I don't know all that the pro one can do. But even the free version has A LOT of tools you can use, I haven't even figured them all out yet. But one that I have used is their Content Optimizer. You can take a new or existing content piece of yours, and compare it to one of your competitor's pieces on a similar topic, and see where you might be lacking based on the keywords that are used in each piece.
Unlike similar tools, Serpstat is a page-oriented platform for in-depth competitive analysis. You can find competitors and define missing keywords for a single URL or even entire domains. You can also view historical position data for a range of pages organized by phrase, as well as see which pages have dropped in rank and their rank distribution as a percentage, which is very handy if you want to compare data from two different time periods or observe changes over time based on algorithm updates and other factors.
In a nutshell, Long Tail Pro helps you quickly find keywords in bulk based on a seed keyword that you input. In addition to returning hundreds of related keywords, the tool also shows search volume (monthly search volume), advertiser bid, number of words, rank value, and my favorite Keyword Competitiveness (helps you judge the competition and keyword difficulty).