The problem can manifest itself in several ways: I am writing this for the whole world to see. If I pick an audience, I will be leaving someone out, and I want the biggest audience possible. I want to write about everything. I can’t do the traditional “get to know your customer” marketing stuff because my blog is free, so I have no customers. What could I possibly say that someone else has not already said?
The fact of the matter is that anyone could read your blog, but very few will. At first the only people who will read are people you personally invite. Then hopefully some of them will recommend your blog to others. Over time the majority of your readers will be the ones who are interested in what you are talking about. But first, your friends need some way to decide who they should recommend your blog to? This is where choosing your niche is so important.
You need to have a focus or central theme that runs through all of your posts, so that when someone looks at your blog they can decide whether they want to subscribe personally and who they should recommend it to. One great post or a link from a high traffic site will get you a lot of visitors to a single post, but to keep people coming back you have to show a consistent track record of talking about that topic frequently over time.
When you write about a topic frequently it becomes your niche. Your friends (or the people you have personally invited) will be able to tell which of their friends are most likely to be interested. Also search engines will pick-up on the fact that your blog is about (your topic) and will start sending interested readers to your blog when they search for related topics.
When new readers arrive they will glance at a few posts and in a matter of seconds will decide whether to come back or not. If you have identified and written about your niche, people who are interested in that niche will stick around. If your topics are too scattered, people will think, “Well this one post is interesting but the rest of it is not interesting to me. If I subscribe/bookmark this site I am going to have to spend a lot time digging to find the posts I am interested in.” Then they will go back the the search engine and only visit again if you hit the top of their search again.
So find your niche. Decide what you want to talk about most. It could be something you are really passionate about, a hobby, your work, etc. Whatever you you pick, write about that topic almost every time you post. Even if you post about something off-topic, add at least a paragraph tying it back to your main topic. If you do this right you will soon own your niche. By that I mean, whenever anyone is searching for a word, phrase, or topic that is close to your niche, they are very likely to find your blog on the first page of results.
My niche topic is helping the west understand China so they can help and not hurt the millions of people there who desperately need our help. America and Europe have been like “a bull in a china shop” for the last two hundred years. They are making a mess and can’t get even get out without breaking even more dishes.
Now, if you search for the word “china” you are not going to find my blog in the first 100 pages. China is huge both in geography/population and as a topic, but there are several other search words you can use and you will find me on the first page. I am working now to consolidate those around my core mission and move the center of gravity away from one particular post several months ago (even though it was a fun post).