I wrote my first successful blog on technology, cell phones, android computers etc.
Although it wasn't a complete success until 5 years later when I started getting a monthly payout from google adsense and enough to almost live off of.
I keep my blog successful by continuing to write articles for my blog and posting a weekly blog posts.
When you get your blog to be successful you can't stop working on it you have to continue to work on your blog writing stellar content to keep your blog a success.