I want to write a blog post building upon someone else's paper, how can I properly cite/credit them? I want to write a blog post which builds upon an author's paper.

He uses a formal notation and academic language for describing his findings, I want to rewrite the author's examples in simple and more popular programming languages, and use a more casual language to explain the same concepts. I don't know if this is a relevant detail, but this is also not the only goal of the blog post. It covers other related subjects as well.

As someone outside academia, I wonder if this is considered OK and how can I properly credit the author.

Also, is using a standard citation format and clearly indicating the source of these ideas enough?
You have two issues to deal with. If you properly cite and attribute the ideas to the original author, you avoid plagiarism issues. If you don't copy too much, but properly quote, from the paper then you avoid copyright issues. 

But, ideas are free to use and to adapt. Simplifying what you find in a paper is a good thing to do. 

One doesn't obtain ownership of ideas by writing a paper. 

I therefore see no ethical issue at all with what you suggest.