Updated on Mar 13, 2019
All images have alt tags - When a search engine comes across an image, the engine cannot visualize what the image is about and has to rely on alternative text for help. Setting alternative text is an important part of adding images to your website and its SEO.
Exact keyword found in an alt tag - While filling out the alternative text for an image, make sure to incorporate your target keyword in it.
Exact keyword in an image file name - not as important as the previous point but still viable is the process of naming your image files and adding your targeted keyword in their names. However, if you use a lot of similar images and have a specific way of organizing them by name you can skip this part.
No underscore found in image file names - Again, the use of hyphens is more viable than using underscores in your image file names. This is due to the Google algorithm being written to understand hyphens better.