I’ve been blogging with WordPress for almost a decade and whenever I meet a new person who wants to start a blog, I can honestly offer this piece of advice … write about only one thing. It’s easy to want to write about lots of different things on a blog, especially because we all have so many personal interests but the truth is that your blog has almost nothing to do with you, it’s about your audience and what they want to take from you.
Much like celebrities, your job (as a blogger) is to give the audience what they want, not what you want to give them.
If you want your blog to be a success, pick a subject and write about it. You can always start another blog and talk about something else later, but remember that each blog has a specific audience.