After doing my first few blogs, I found these were the most common errors I would get:
Error #1: Keyphrase in introduction: Your keyphrase or its synonyms do not appear in the first paragraph. Make sure the topic is clear immediately.
Solution: Make sure your focus keyphrase is used in the first paragraph of your post. Note, this is the first text widget you use on your page (not heading). Once you have that updated, Update your post and see if that corrects the error.
Error #2: Keyphrase in title: The exact match of the focus keyphrase appears in the SEO title, but not at the beginning. Move it to the beginning for the best results.
Solution: Review your SEO title again and make sure you are using your focus keyword at the beginning. Once you have that updated, Update your post and see if that corrects the error.
You may stumble across other errors but WordPress does help by providing links with more detail.