Try following the goal indicator at the top right of the screen while editing your hub.The top tiers of these goals (at least in my experience) are: 1250+ words, at least 3 media items (pictures, videos, etc.) and at least 2 reader engagement capsules (quizzes, polls, etc.). This should help yo get through the evaluation and ensure it is published as featured content, though it is not the only consideration made. Make sure your titles and subtitles are specific and related, and make sure your content is original and to the point. Hope this helps.