You may not know this but wordpress setting quite often create loads of duplicate content.
This can hurt your SEO score or devalue good ranking pages on google.
Google is getting a little more laid back about duplicate content for many reasons especially when it is on your own site but for good clean seo it is best to clean it up.
STEP 1 CHECK FOR DUPLICATE CONTENT
There are many ways to check for duplicate content.
Check out http://www.siteliner.com/ for your sites duplicate content.
STEP 2 REMOVE DUPLICATE CONTENT FROM WORDPRESS
Install an SEO plugin for wordpress. Yoast is a good choice and is free.
Yoast SEO plugin link.
STEP 3 SET UP YOAST CORRECT TO PREVENT ARCHIVE DUPLICATE CONTENT FROM WORDPRESS
Make sure you set yoast to these settings shown on the images below to prevent search engine bots from indexing Tags, Categories, Author and Archives.
(You may actually want your caegories pages indexed by google as it helps your pages get fount better by google. Look into this one it may vary depending upon the way your site has been built.)
You may want content indexed off of my main index page url, and block the archives author, category, tag, date.
STEP 4 REDIRECT ATTACHMENT URL’S TP PARENT POST
Use Permalink setting of Yoast SEO plugin. To do this set “Redirect attachment URL’s to parent post URL.”