The second question to ask yourself is "What if everyone in the world saw this web page?". By everyone, I really mean everyone, your parents loved ones, friends, co-workers, etc... You have to be comfortable with anyone seeing any web pages you put on the web. Though you may have a different primary audience in mind, anyone can read what you've published. This is particularly important when it comes to blogs. Remember, a blog is not a private diary that you keep in a locked drawer. A blog is a document in the public arena that absolutely anyone with an internet connection can rightfully read whether you want them to or not. Also remember that this fact applies not only to blogs, but to all different types of documents on the web.
If you still decide that you want to hide some of your web pages from robots, preventing them from being indexed in search engines, you should be well aware of two major limitations. The first limitation is that a robots.txt file will only protect files from robots who obey robots.txt protocol. All of the major robots (Google, Yahoo, MSN, etc...) do obey the robots.txt protocol, but there are a number of robots who don't, and they may gain access to your files if this is the only protective measure you take.
The second limitation is that a robots.txt file only affects robots and will have no effect on any human visitors whatsoever. So again, you will have to password-protect sections of your website that you don't want people to see.
Asking yourself the questions presented here should help you filter what information should go onto your website and which information is best left outside of the public eye.