Jason well, a good blog post must be understandable easily. There shouldn't be excess images, that would really confuse the readers. You need to provide some elaborating images, that should help the readers to get a clear idea about the subject.
Atleast, you should know what you are actually covering in the post. If there are some statistical data in your article, you should avoid giving any images for that. Provide images only to elaborate a situation. 😄