If you are writing a blog, and you are not a web designer, but you want your blog look professional. You'd better hire someone design it for you. If you are interested in designing blog, you can learn it by yourself. One thing I want to remind you is, before you decide to design your blog, you'd better seo blog for more information about designing blog. Because you want both search engines and visitors love your blog.
For me, I care much about my readers, other than search engines. In my opinion, visitor is the key to my success, I will be nothing without support of my readers. So I spend most of my time on thinking what my readers like, then I will write something about that.
Design is the face of your blog, people are judging blogs by their looking, because they don't know their contents at first glance. So design is very important for your blog. You may say that there are many templates that you can use, what I want to say is it is not a good idea to choose a template without any redesigning. So learn something about design is always good for you.