Consistency is key. As Bigu_c already indicated, your font size is too small. It's actually going beyond that, you are applying different font sizes all over the place. Find consistency.
Your right side rail is really way too small, for someone with bad vision, it would be impossible to read which is immediately resulting in a lost user.
Depending on how serious you are with your blog, get a logo made, some indication that's making you "special" and helps your readers to retain your branding image. Favicon helps too. Look at your own toolbar and check how many sites have a FavIcon next to their link? It's just a minor detail but it goes a VERY long way.
IB