Firstly understand:
1. There is a thing called Google Images. It's right up there on the top right corner of your Google search page, next to Gmail. It's something that you may not give much thought to. It's the way to visually discover information on the world wide web.
2. Many people use Google Images to search for images for a variety of reasons. They may be looking for a quote or an infographic, a template or a specific type of picture.
3. It is easier to be on the first page of Google Images than it is to be on the first page of Google Search. Why? Firstly from my own personal experience over many years blogging, with multiple blogs I have seen this and secondly because of the many number of images that are shown in Google images as compared to the 10 or so on Google Search.
4. You must have an image in your post to get social media re-shares. Optimally it would be good if you had a Pinterest size image on, or hidden in, your post so that people will share your post on Pinterest.
5. Google reads text so you have to provide text to your images. Google's crawlers cannot see your image so any words you provide in the filename, ALT attribute and caption help Google to rank your images in Google images.
How to optimize your images to get more traffic.
This is a simplified version of what you must do to get the best views on your blog images and therefore your blog. It's as simple as ABC:
A. Save the image on your computer, in pictures, or downloads, with a name relevant to your post. As an example let's consider a post about The Benefits of Walking. The image below was called 'Image00957' and I renamed it 'walking benefits'.
This way Google will read it as
<img src=”walking_benefits_.png”/> which is helpful.
Whereas <img src=”IMG00957.png”/> is not helpful at all.
B. Make sure you use the ALT attribute on the image, when you put it in your post. Alt text was designed for visually impaired screen readers to explain what the image is about. It also gives Google extra information about the image. Try and use a relevant keyword in the ALT text to describe the image, if it is relevant. For example in the image above the ALT attribute could be ' two people enjoying the benefits of walking in nature'.
C. Use a caption under the image. Did you know that this is often the most read text on your page? Also it gives google extra information about the image and your post. The example in the image above could be 'Jimmy and Lee are getting out of the house and enjoying the many benefits of walking every day at their local parks. Here they are seen at the newly updated Gannons Park.'
Ranking your blog image in Google Images.
Here are the ranking elements that Google uses according to Rand Fishkin of Moz
A. The image file name
B. The alt attribute on the image.
C. The image caption.
D. Surrounding text content.
E. The page title
F. The page URL
G. Image engagement and popularity.
H. The image dimensions matter.
I. Image size.
J. Embeds of the image.
K. Traditional web ranking factors on the existing URL.
L. Image relevance and visual match
As you can see there is a lot more to this optimizing images thing but if you just make sure you are doing the ABC described above you should start getting more traffic from your images.
Go to Moz to see more explanation of these elements A to L elements of ranking images and also an in-depth video on SEO for photos, visuals, and graphics.
Bonus tip for getting more traffic by using images.