I recently helped two people makeover their WordPress websites. Both were excellent professionals in their respective careers but had no web design experience. Although I was able to help them both in multiple ways, the most effective way that I helped them was to reduce the number of items in their menu.
Why are an excessive amount of items in the menu a problem? When a visitor comes to a website, they need to know what to do next. If there are too many choices to read, they may just leave. Also, if one choices is more important such as your blog, it will not stand out as much from among thirteen choice as it will among three or four. Part of the problem might also be that some people have WordPress set to add all new pages to the top-level menu automatically or are unaware that you can create sub-menus simply by indenting items in the menu area.
I was just saying to my wife that when I go to a restaurant, I get worried if I see too many things on the menu. Can one chef prepare so many dishes well? I think a well-organized menu with a limited number of options and logical organization into sub-menus (but not more than three layers deep) gives a visitor more confidence in the web site and its owner.