Recommendations needed for SEO software

[peppergomez]

For the last few months at work we've been using Google Adword's Keyword Planner, and making sure that we are adhering to Yoast's SEO optimization within Wordpress for each of our blog articles. We choose search terms ( a single search term per article) that have on average between 30-500 searches per month. We don't have anything to show for it in terms of sales or improved Google search returns.

Which makes me think that we might be doing something wrong. None of us are specialists at this kind of thing.

If anyone does SEO for a living or has more than casual knowledge of it, can you suggest any sofware apps that can search for the terms or at least assist in the search and implementation process?

Thanks.