Disclaimer: While I am a believer in the value of a blog to build your business and communicate with your clients, I do not currently have my 1000 Words Photography Blog up and running. I am very much enjoying contributing to the KEH Blog for now. That being said, I have learned a lot over the years, mostly by trial and error, about what kinds of posts attract an audience.
1. Catchy post titles. I know you have clients that want to see their session on your blog, and you should cater to them of course. It's great for business to show your work off. But if every one of your blog posts could be titled "Here are some photos I took of some clients" then you are missing an opportunity. Try finding something quirky about each session and using that as the post title. "Adventures in Babysitting" for a sibling group with a crazy toddler that wants to crawl all over everyone else might make a reader stop and pay attention more than "The Smith Family". Something along the lines of "In This Week's Episode of What Not To Wear" should draw attention to your article about dressing for a session. And that leads me to the next tip...
2. Articles with information that is helpful to the client. What to wear is a great place to start. What to expect at your newborn session is always popular because it is a relatively new specialty. Other helpful (to the client) post ideas: Choosing the perfect location. Best wedding reception venues in your area. Why hire a professional photographer. How to store and backup your digital images. Basically these posts are short classes for your clients and potential clients. They will appreciate the information and look to you in the future for their portrait needs.
3. Make it personal. Use examples from your own experience. We all do things a little bit differently which gives us all the opportunity to post on the same topic with completely different points of view. Don't copy and paste information that you've read somewhere. Put it your own words with your own personal spin. You don't have to have a revolutionary, completely original idea to post your thoughts on your blog. Share you own personal experience with the topics you find interesting and it will make for more enjoyable and informative reading for your followers.