Folks working in PR are some of your best sources. Pick out the top ten PR firms in your city and mail them announcing your freelance writing spiel. They will add you to their media lists and send your press releases. You can mail them for your source requirements. Often times than not, they will jump at the opportunity to help showcase their client and willingly help with scheduling interviews, getting images, etc.
HARO – This website is a Godsend. One of the oldest around, Help a Reporter Out is a site where you can register for free and share your pitch. This goes out to their entire database and sources contact you if they are willing to share their thoughts. Alternately, you can respond to one of the pitches if you’d like to share your thoughts. All types of print and web media, national and local, have their calls for sources on here.
Publiseek is much newer compared to HARO and only recently signed on with them. I did get some good sources for a story I was doing, they cater to a more international audience I believe but I could be wrong. Anyways, another free avenue for sources to use in your articles. Sourcebottle is another such site. Yet to find much use on this yet but have signed on and hope you have better success than I.
Twitter has been an impressive channel for sources. I have put calls out and received responses not only from the folks I am directly connected with but also many others that I can reach given the followers I have. And I don’t even have many to boast of so it is still a very effective tool regardless. I have also received story assignments based on those calls for sources so you never know the wonders social media might work for ya!
LinkedIn is a great place to ask for sources especially if you have a large circle of connections and the stories you are working on are more relevant to the professional/corporate types. Not as much clutter here and your referrals will be through friends, not unknowns, so if that makes a difference then venture on over. If you are a member of certain industry-specific groups then you can also share your call for sources there directly.
I have a lot more avenues for finding sources for stories but these are a good start. I will discuss the rest multiple posts later. For now though, hope you have enough folks to talk to for a good stories with relevant quotes and expert opinions. Forge on!