I don't have a portfolio site, but was successfully freelancing on the basis of referral for four years or so. I wouldn't take a random client on, because bad clients cost money. Reach out to anybody who trusts you to "get the job done" and get them to reach out. Networking and trust are essential.

Another idea getting your foot in the door as a freelancer at an agency. About 1/4 of my work (and best paid work) came that way. Gives you a client base to build from (though not your clients, it will give you demonstrable experience)