In a 3 year old post How to build traffic to your blog, I have mentioned that it is good for SEO (Search Engine Optimization) to include key words in the blog URL and that search engines cannot distinguish between words in a compound word like for example http://bloggerfordummies.blogspot.com. This I learned from WebCEO. I got to thank a reader whose blog is Inside that ad who asked about changing the blog URL to include hyphen whose motivation to change was that old post. I am grateful that he has drawn my attention to that post which reminded me that I need to do an update on that post. I got to state here that what WebCEO taught is not true because you can try to google, for example, blogger for dummies, and you will see in the results page that the 3 words are highlighted (bold). this showed that search engines can separate out words in words combined into a single compound word. Thus if you have something in your current URL similar to bloggerfordummies, do not try to change the blog URL especially if it is an old blog as you will get dead links and will have to start all over again. I for one will only change to something like blogger-for-dummies only if bloggerfordummies had already been taken but I still want the words blogger and dummies in the blog URL.
One further thing. There are people who said that 1 or 2 hyphens may be OK but more than that, the URL becomes spammy.