Blog posts should not be more than 600 words long; the shorter, the better. Even a haiku qualifies as a post. Chances are, the shorter the post, the more likely it is the whole thing will get read. (If you’re not a photographer, Unsplash has many high-quality images you can use, no attribution required.)
Blogging is one of the many ways you can build your author platform. What’s great about it is that you can have it set up to automatically post to other social media sites, such as Facebook & LinkedIn. https://sarahleastories.com/2015/10/08/12-ways-to-build-your-writers-platform/
Have theme days or regular feature articles. This helps you stay on track, as it’s easier to write a continuing series than a stand-alone piece every single time. This will also help you blog purposefully, rather than simply posting whenever inspiration sparks (which doesn’t come as often as you might think). Serious bloggers should blog at least twice a week (& no less than once), preferably on the same days. Make your own deadlines, & meet them.
Blogging is a terrific way to get instant gratification (i.e. feedback) while still writing for professional publication. http://www.writersdigest.com/editor-blogs/there-are-no-rules/8-blogging-tips-for-writers-to-find-success
Coming up with categories for your blog will help generate ideas. Mine include Homemaking/Marriage/Motherhood, Food & Recipes, Mormon Culture, etc. One of my personal favorites was Micropoetry Mondays, with each set of micropoems having a theme. https://sarahleastories.com/2017/08/08/micropoetry-monday-mystery/
Every April & November, I participate in the Writer’s Digest Poem-a-Day Challenges (as well as the Wednesday prompts the other months). I post the answer to the prompt daily on my blog, which gives me time to build up my regular feature posts (Monday’s Sweet Little Nothings & Fiction Fridays). http://www.writersdigest.com/whats-new/2017-april-pad-challenge-day-4
A blog is a piece of literary sculpture that never dries.