Changing your blog's URL may be the stupidest thing you can do, especially when you have gained some readerships (that is, visitors). Ok, in today's tip let me shortly outline the dangers of changing your blog address. I urge myself to write this article when I realized that many of our fellow bloggers have unconsciously made this mistake.
First thing first, why would someone change their blog address? One main reason is that they did not plan their blog properly from the beginning. For example, they made their blog in 2008 and use the URL 'blablabla2008.blogspot.com' (only example!) and suddenly they found out that today is already 2009! So will do they do? In order to keep their blog 'up-to-date', they'll change the URL to 'blablabla2009.blogspot.com'.
Now imagine that the owner have worked very hard to get visitors, and let's say that the blog gets 200-300 visits a day. Many people are following and have bookmarked the blog. They like to visit the blog daily because it is always up-to-date (remember, it's only an example). Suddenly, the blog is no longer accessible! And when they try to open 'blablabla2008.blogspot.com', Blogger will only return the Blog not Found page!
After a few days, the unknowing owner of the blog did not see any more comments nor followers appearing in the blog. And guess what? He has just lost all his visitors! It's pretty terrifiying and I'm quite sure that you won't like it if that happens to you.
Another danger lies within search engines' result page. As you already know, when you click on one of the search results, you'll be taken to that specific page. And say that someone click on the URL 'blablabla2008.blogspot.com/2008/01/article' because they found it is related to what they are searching for. Without the need to think, you'll spontaneously know that the page no longer exist! That means that the owner of the blog has just lost some potential visitors from search engines. This may not be much, but imagine if it is 3 visitors a day, it will result in 1095 visitors lost at the end of the year!
All in all, changing your blog URL is a risky thing to do. My suggestion to you is the usual phrase 'think before you act'.