Creating work for yourself keeps your skills sharp. It's also the biggest part of your portfolio and generally the only thing you can show prospective clients. Keep in mind the various sectors of design you want to get into- album covers, logos, illustrations(if you do that), etc. Create personal art for as many of them as you can.
I've had a few clients, but started doing free requests a few months ago on DeviantArt simply because there is very little freelance work for my industry and skill level. I use those designs in my portfolio and listed as clients. If you have client work, ASK them prior to including it to your portfolio. Legally it belongs to them. For your personal work, consider looking into a cost effective way to copyright them or prove it belongs to you. There is a TON of art theft happening. Many from foreign, Asian countries. I know a few artists struggling to get their work removed from these thieves.
Sign up at www.deviantart.com. There are big name artists using this site as well. You can do commissions directly on DA or provide a link to your site. Research what the average rate is for designs. If you do not have a large portfolio or your skills are sub-par, price them slightly less than others. Don't expect a client to pay the same price or more than what an established designer is charging.
Create a profile on http://www.behance.net/
or any other portfolio site. It's best to use free services until you make enough money to use larger, better sites. Participate in contests/project sites: http://www.talenthouse.com/
Look into www.skillshare.com classes. Read books online or go to the library. Research CURRENT laws and rules about freelance work and legal rights you have.
Also combine your twitter, instagram and tumblr accounts. Don't have them, get them. Almost every major creative business has one. Your focus is about spreading your work around and networking. *Note- some social sites only run on smart phones*
Best of luck