What Makes A Client-Converting Portfolio?

A year ago I wrote an article on why every freelancer should have a website where I shared the 5 top reasons why I decided to have an online portfolio as a fulltime freelancer. One year later, my principle has not changed. In fact, I believe that the importance of online presence is an element that every business owner should embrace. Why? Because this time, my online portfolio brings in almost 90% of my clientele with at least 2 to 3 enquiries a week, that's a total of 12 enquiries a month. How do I do it?