I believe that writers mostly write from experience. Of course, that doesn't mean that mystery writers have murdered, buried the body in the woods, and eventually caught. That model doesn't scale. However, the more compelling things, like what characters think, how they feel, and how they think may come from having experienced similar thoughts and feelings.
When it comes to blogging, a similar approach can help. If you are writer blocked, you should probably go out and do something. Either your activity will form the basis of your writing, or it will jog a memory of a similar experience or idea that you had in the past, which you can write.
What you do is up to you. It can be something new; or it can be something you have done 1000 times. Even if something is not new, you may notice some nuance that you can use as the basis for your blog post. Again, do something. You'll be surprised how ideas pop out of the strangest places.
