If you are running a professional blog then you know that it is all about content and not about how your blog looks. When we talk about content it is the Title and the post content of your blog. Any reader of your blog, is interested in these two things only. When we say reader that means he’s here to read something and that’s what exactly is the point. You have to make sure that your content is easily readable. When you use big fonts in header and posts, your readers can read the stuff without any trouble. I have seen many blogs using very small fonts. No doubt, their content is interesting but the problem is it’s a bit discomforting to read small fonts. On the other hand if the content is in big fonts then it flows like butter on a toast.
1) If your theme is using small fonts then you can easily change it by changing fonts in the style.css of your WordPress theme.
2) or you can have a makeover of your blog fully by installing a new theme. I would recommend Genesis and Thesis themes. All the child themes of Genesis and Thesis are using big fonts and that’s the very reason these theme frameworks are just perfect for pro blogging.
You might want to check their other features which are rather more interesting than just the fonts like SEO, loading speed and stuffs like that which are indispensable for a professional blog.