don't fell that your posts need to be highly original or profound. Simple summaries of material from the text are helpful. For example, look at some of these posts I wrote on my blog about the text. Writing these posts helped me focus on the essential features and hopefully are helpful to others.
Also, it is good to keep emphasizing quantitative aspects of what we are learning (especially equations and graphs of experimental data). This is what distinguishes biological physics from biochemistry.
For reference, it will be good to start adding labels to posts, e.g.,
chapter number, diffusion, physics vs. biology, random walk, DNA, ...