For any blogger, the question - how successful is your blog is a tough one to answer. I believe there may more than 200 million blogs as of today.A quick look at the wordpress.com stats that it publishes indicate that close to 45 million new posts are created each month. In this context, making your blog successful is a tiresome job; Well, it may not be as much if you consider these three factors - Technology, Content and Consistency.
This is by far the easiest factor one can take into account because of the fact that the usage has become very simple even for kids. However the catch here is to find out the critical must-dos to be covered in this. By technology, I mean aspects like the platform you use to host your blog, how much sophisticated you get to measure your performance and the likes. Platforms like wordpress with its huge ecosystem of contributors through plugins has made the part of technology the easiest and fastest aspect one can tackle. I would consider this as the foundation stone to the success you expect for the blog. While there are plenty of things you can do, the main ones would be things like choosing the right blogging platform, tracking performance using either the in-built statistical capabilities or using tools like Google Analytics, and hygiene factors like setting up RSS feeds,publishing in directories and avoidance of HTML faults.
We have heard from many industry experts that SEO is currently moving in the direction of content marketing. Search engine algorithms are becoming more and more intelligent to understand whether a website really add value to a reader. Many of the SEO techniques used few year may be irrelevant, obsolete or even have negative impact today. Today, the internet is literally becoming a place where content makes the difference. You may be able to drive traffic to your blog by various techniques, but to sustain it - your really need the useful and relevant content your target reader is expecting.Content has gone beyond the page that you own - today -- it's about how much you genuinely contribute through the social channels and also how others are expanding it. Today your persona is more important when compared to the impersonal platform.
This is a factor that is true not only in the blogging world; but also for any of your communication channels - whether it is social media emails. Unless you are consistent in writing; there is no incentive for reader to come back. No one is free enough to check every now and then on whether you are writing something and which is making sense to them. Consistency indicates you are committed to what you write about; that you are genuinely interested in sharing the information. There are various theories and expert opinions on how much is consistent; but I think - it's really up to the domain you are in; the bandwidth and the expectations. For example a blog like allfacebook may even have multiple blog posts per day; while a personal finance tip sharing blog may have only one per week.