On my own wordpress.org blogs sites, and on others I am using the following plugins.
This is great if moving to self hosted, or a theme where you will be using thumbnails. and have lots of existing posts that don’t. Instead of manually going through them all you can use this and it will take an image from the post and attached it as the featured image. A compete time saver.
This adds a row (you choose how many) of thumbnails after each post that relate either by tag or catergory (or both) to that post. A great way to get your reader to carry on clicking around your blog.
The widget can use photos from your Flickr, Tumblr, or Pinterest pages and displays them on a WordPress site. You can choose how they are displayed in a row or slider. It has lots of options to configure it exactly how you want.