Here many may be probloggers or some may be amateur in blogging. Out of many blog posts you wrote many/some have ranked well in SERPs. So what was your reason behind that blog post ranking. Share your ideas to make our next post rank well. May be i can have commentful of ideas. Ideas can be related to any niche, may be Long Term or Short term (event).
Here On page SEO matters a lot. If you done a proper On page SEO, then you can rank in SERP for sure
@justin, it depends upon various factors like Keyword in the title tag, keyword appearing in the H1 tag, keyword density, content length, originality and uniqueness of the content, URL structure, links, social shares, etc.
Also what @Rajkumar says is true.
If your competition is too low there is no need of intense optimization. I had a post at my blog which talked about “Introverts”. It was ranking well even without any SEO tweaks.
I hope that answers your questions.