If you want to start up a blog, the best thing to do is just find a topic you care about and get started! If readers like what you post, chances are they will come back to read any new posts. A popular, interesting blog can be built by anyone, focusing on topics that range from telling jokes to showing photographs.
Update your blog frequently with new content to keep your readers coming back for more. Great blogs usually post at least one time a day. If this seems intimidating, try coming up with a few weeks worth of content before you take your blog live. Having standby content will ensure that your blog never gets neglected.