The Google Keyword Tool is SUPER helpful for building a foundation for your keyword research strategy. At the end of the day, these search numbers are coming straight from the horses mouth. You can filter down to a hyper-local level and see which keywords are getting the largest search volume. Plus, with it’s integration with PPC you can get a quick idea about commercial intent by looking at the bid and competition metrics. How much are people bidding on KWs, higher = more likely to generate a return. Usually its aligned with search intent. That said, the trending data is a little less reliable. I would still use Trends to analyze the popularity/ seasonality of KW search volume.
Checking if your site is indexed properly is essential. You can do this inside Search Console. You need to make sure that all your pages are crawled and indexed and that you don't have any 404 errors or other page indexing issues - which includes the AMP (Accelerated Mobile Page) indexing issues - should you already have submitted your AMP powered site for the mobile index.
By quality of the post we are basically talking about the overall authority and ability to engage. A post with low quality will eventually get lower engagement levels by users and that signal will be passed down to Google eventually - that will result in loss of overall quality score of the site. Churning out content that is put out for the sake of driving blog post numbers and not the users - is a failing strategy.
I recently paid to use the moz keyword tool, and its been really insightful. (but expensive!) it helps find synonyms and other wording that i never would have thought to include in my post. also, i’ve realized the importance of allowing comments on blogs, as people discussing the topic seem to add those terms naturally to the post. thx for the post!