Freelance writing demands a portfolio so clients can see your level of writing expertise. (Even writers of fiction can make use of a writing portfolio. Read tomorrow about that.)
I've never bothered with the online portfolio sites to display writing samples and showcase my writing skills. Usually, the sites are cumbersome to navigate and take far too much time in uploading writing samples. Plus, it's just more URLs and passwords to have to remember.
I've always thought it was far easier to set up a website or blog and use that as your online portfolio. That way you control the content, the URL, etc. The portfolio site can't suddenly change its Terms of Service and commandeer ownership of what you post. (Sure, Facebook failed in their recent attempt to claim ownership of posted content, but who has the time to mount these campaigns to make a site back down?)
I love blogs, especially because you can use your name for the blog and that will be your URL i.e. MaryJones.blogspot.com or you can use your handle that you're known by on a freelance writing site i.e. NewYorkWriter.blogspot.com. A name is much more appealing than a portfolio site with your identity being a string of numbers.
I think Blogspot is the easiest platform I've used. You can personalize it every which way from Sunday so it will be more memorable than just another segment of a portfolio site. You can use 3rd party templates, and some of them are really beautiful. Plus, it's so easy to update.
Spend time making your site look professional. Decide the editorial content and select Labels accordingly so clients can easily find something that fits what you're pitching to them. For example, for a portfolio where your talents lie in business, technology, finance, and marketing, those 4 categories would be labels on your blog. You designate the posts (articles you write to showcase your talent) by the respective label so if a client wanted a technology writer, he could click Technology and find all the articles you uploaded.
Start a blog and make your content fit the categories for which you want to be viewed as an expert writer. Then start filling the blog with articles that fit your categories. Aim for at least two articles in each category.
When you talk to a potential client, you can point them to your website or blog, the best showcase of your writing skills.
Basic Rules For Freelance Portfolio
1. Figure out that for which you want to be known as an expert.
2. Make your Labels or Categories reflect those niches i.e. Family, Health, Home, Travel, etc.
3. Write one article for each category immediately.
4. When that's done, write another for each category.
5. Market yourself as a competent, professional writer who adheres to deadlines, produces excellent work, and maintains the highest standards in dealing with clients and the confidentiality required by those business arrangements.
6. Proofread relentlessly.
Take advantage of the free blogging platforms because less overhead means more profit.