There are several aspects of a published piece of content that suggest that it is optimized for SEO. Below are a few important things to note. Please note, this is a general guide, there are many things that can be done that will not be mentioned here.
Ideally, you want the content piece to have heading tags applied to titles. One H1 should suffice for the main blog title followed by H2s for every paragraph's titles. H3s are usually not used but can be applied if necessary.
Optimized meta tags
Make sure you have both a meta title and meta description. Both should be captivating to attract traffic and have some form of consistency with other meta tags throughout the site. Proper character lengths should also be taken into account.
Images with alt texts
Images don’t just help search engines index the images on the blog, but provide nice breaks in the content and helps readers stay engaged. In the backend, alt texts applied to the images are what helps search engines know what the images are. Appropriate alt texts describing the image should be applied to help with search engine crawls, screen readers for the visually impaired, and if done correctly, can help rank a keyword on the blog itself.