How to build a content writer portfolio from scratch
So, I have been in this niche since the last couple of months and I still don't know how to make a portfolio. Medium and LinkedIn seem to be a nice platform but the fact that I don't have any published articles act as a barrier in my career. I am currently ghostwriting for several clients which is why I don't have the authorship.
Would really appreciate if you guys can drop in your suggestions.
I feel your pain. A lot of my early work was ghostwriting (bylined as companies, CEOs and other senior team members). If you are freelance, I would definitely recommend adding a portfolio permissions clause to your contract. Here's a good sample clause from Law Insider.
The other thing you might want to consider is curating a private portfolio. If you have a website where you're promoting your services, create a page which is locked behind a password. Add a note to that page, asking visitors to email you for access. You can also achieve the same with a portolio hosted on Dropbox or Google Drive. Also, it can be worthwhile creating a few writing samples that are hosted here too - examples of your work for fictional clients. These give potential clients an idea of the writing styles you're experienced in and types of content you can produce, without needing client permission.
And, finally, I definitely second @MiaSrebrnjak's point on collecting testimonials. In many cases these will be just as influential as portfolio entries themselves.
I've checked a couple of articles and many professionals in the industry recommend maintaining a testimonial catalog. Some also recommend including a portfolio permissions clause in your contract - I found this article helpful if you wish to check it out!
We also collected a couple of portfolio tools which you can use to build your portfolio, you can see them here. I hope this helps!