This post is from a low-reputation account and contains an unverified outbound link. Be cautious before clicking external links.
This video sets out the concept for posting blog or news articles to your Joomla site. It explains why they should be structured in a particular manner with Read More Links instead of having complete articles on the News or Blog page in your site.
Structuring your blog posts in this manner will do a lot for telling you which posts are attracting the most traffic.
Free images for use in blog posts can be found at http://www.pexels.com and https://unsplash.com/ but there are several other free image sites around.
May your blog posts bring you much traffic and lots of quality comments.