If you're looking to do keyword research for your website, i highly recommend kwfinder.com. They used to have a free option without signing up but i guess they realized how good they were so now they force you to sign up.
The good thing is that so far, they don't ip track you but i'm sure they will eventually.
Number of Searches
So here's one that i did for Standing Desks. The most valuable thing here is the number of searches for the keywords. AdWords used to give you this information but now they only provide you with a ballpark figure that has such a wide range that it's useless.
The next most useful piece here are the 'related keywords'. Sometimes you might want to target them instead if they get more traffic and have less competition. A lot of the time, however, they're words and phrases that you want to include in your post so that you seem like an authority.
The final piece on this page are the competitors. If there is really difficult competition for a keyword, then i usually wouldn't bother. If the competition is Green or Yellow, then it's definitely worth a shot to try and compete. Amazon listings are particularly attractive to compete against.
If you're a business owner with a website, then i'd strongly recommend that you get at least a free access to the KWfinder tool. Especially if you're looking for new content to add, this will help you get more bang for your time and effort. No more shooting in the dark and hoping to hit the target.