A column is an author's opinion, your thoughts on a topical issue that you want to share with others and discuss in comments.
Choose a clear but catchy headline that intrigues the reader and at the same time expose your opinion.
Don't be too wordy, you don't need a stream of consciousness. Of course, an author's column is not a tutorial where you need to be clear and just on business. But if you can fit a thought into one sentence, don't stretch it out by ten.
Don't write it dry though. Reason things and present them as if you were arguing with a friend drinking beer.
Give examples. You can even share examples from personal experience.
Don't grab the biggest piece of the pie, do not engage in self-love. The opinion is definitely yours, but with rare exceptions the reader is interested in the essence and course of your thoughts, not in your persona.
Give arguments. "I think so" is certainly not an argument.
How the developers pass through job interviews
Social networks are very common now, and we all have profiles there, of course. Someone has blog on Habr. Anyway you can learn something about almost any of us by reading a blog. At interviews developers are often not asked any more questions about programming, believing that if a person has a successful technical blog, it means that he or she is no less successful in his or her work. Such a developer may receive even more job offers than someone who has many projects at Github.
Developers are now measured in views and subscribers — and that's wrong
С недавних пор меня просто заваливают Recently I’ve been getting invited to a lot of interviews, and they all go pretty much the same way: I come on, we chat for a while, and then… they make me a job offer. Like I’ve already passed the technical interview stage and confirmed my skills. The thing is, I don’t even have a mega-popular GitHub page with examples of my code, and my CV is so bland it looked like I was forced to write it. The only outside indication that I’m worth something is my ability to answer technical questions, but I’m not even being asked to do that anymore. The reason for that is simple: I wrote a couple of Habr articles and they became popular.
Ideally, you should want to write a column. If you're thinking about what to write about, maybe you should look at a different format.
But in general, there are topics relevant here and now, and there are so-called "evergreens". The actual topic is the recent event under discussion. For example, Satya Nadella publicly stated that tablets will soon "die" and Microsoft will no longer release Surface, while you have all your work built on a tablet and you strongly disagree.
Evergreen themes are always relevant, no matter what happens around: work, health, safety, confidentiality, etc. If you have an offbeat approach to interviewing people or to your privacy it's a good start for a column.