Google image search is a thing. And you want your images to be found and lead the searcher to your blog post. Here's how to optimize your blog images for SEO.
1. Download the image from bigstockphoto or another royalty free image site. If you have your own photos, even better.
2. Rename the image based on the KEYWORD or TOPIC of the blog post.
For Example: The following image when downloaded from Bigstockphoto has this filename: bigstock-Cartoon-Crowd-Network-Proxies-5642112.jpg
You would need to RENAME the image filename and SAVE it on your computer BEFORE uploading it to your blog.
So if you were using this image in a blog post with the title "Why Social Media Marketing Works For Small Business" you would simply rename the photo file as: why-social-media-marketing-works-for-small-business.jpg
(Use all lowercase and separate all words with a dash "-")
3. Upload the image to your WordPress.
4. Adjust the "Attachment Details" on WordPress upload screen to set the image TITLE and the image ALT TEXT to be the same words that you used to rename the file.
For example if the filename is why-social-media-marketing-works-for-small-business.jpg then the Title and Alt Text would be: Why Social Media Marketing Works For Small Business (capitalize the first letter of each word and do NOT include dashes, use spaces instead)
Here's a screenshot:
On the HTML view of all of this, when you're all done it should look like this:
<img src="http://www.convertwithcontent.com/wp-content/uploads/2014/02/why-social-media-marketing-works-for-small-business.jpg" alt="Why Social Media Marketing Works For Small Business" title="Why Social Media Marketing Works For Small Business" />
I know these instructions seem complicated but it's really pretty easy.