It isn't a set rule that you need to post every little thing that crosses your mind or that you need to post everyday (yes before you say anything I know I have). A blog is mostly about sharing your opinions with the world or giving helpful advice; to be honest I started my blog because I wanted to write. Not professionally or anything but it gives me a hobby.
So again (I apologise for the repetition) if you're thinking about starting a blog, do it! What's the worst that could happen. If you get bored and don't like it? Delete it and start a new one, it's that easy. Everyone has to try something once so give blogging a go.
And don't worry. My first blog was a complete disaster. I had a grand total of three posts that were rubbish, so I started again (and again once more) until I created 'An Average Life' and am finding it relatively easy to keep up with. Even bigger bonus - blogging doesn't have to cost you anything!!!
**An Average Life**