Your article is more likely to go viral if it is seen as being practically useful.
Don't worry too much about giving away secrets (unless you're Coca Cola, obviously). The role of such an article is to prove to the person watching that you actually know what you're talking about.
So , you do have to know what you're talking about. Obviously if you go out as an expert and get something wrong, the flack will last forever, so only do this in your areas of expertise.
In Neil Rackham's major sales buying cycle, once someone has decided to do something about a problem they are having, they look around for all possible solutions. One might be "I'll do it myself". Your instructional video or article reaches those people, and if they like it, they'll share it. I shared, for instance, a guide to replacing my phone screen which I'd used successfully.
The value comes back to you from those people who look at your video or read your article and say to themselves "I haven't the time to do that", or "that bit looks hard" and then you have their trust. They can see you know your stuff, so you are very likely to receive a call saying "can you fix this for me?" You'll receive a load of inbound links to your website, too, which will help with SEO, and you might even find yourself at the top of Google for the query you are answering.
Once you have a new client through this, of course, there are opportunities for upselling, building an ongoing relationship through email marketing and to build your testimonials, star ratings & word of mouth recommendations especially if you use something like https://getfivestars.com (I'm a reseller, so if you fancy that, talk to me).
For topic suggestions in your area, I suggest looking at Quora (or any other online forum) to get a regular supply of user questions that might prompt you to write a how-to.
One final thing. When we are expert, perhaps even the definition of being an expert, is that we internalise our skills. They become second nature, unthinking ways of being. This is what you mine to get your article, and so you have to learn how to become aware of what is obvious to you, but a revelation to everyone else.
Get it done by: http://www.surgemarketing.co.uk
For: in the region of a few hundred pounds upwards, Surge Marketing is a content marketing company and this is what we do.