So you've read the books and gotten tons of tips and tricks on how to drum up business. Scour Craig's List for those diamonds in the rough, hit up production houses on mandy.com, present your demo to every casting and talent agency on the web, etc etc. But for some reason, you're not catching on. What are you doing wrong? You have to start local. If the people in your neighborhood don't know what you do, chances are people in other states and countries aren't going to be an easier sell.
Sure, I got my start doing video games and explainer videos for clients across the Atlantic, but that didn't make a career. I really started to gain steam when I simply walked outside and started interacting with my surroundings. I put business cards and postcards out at local businesses. I contacted everyone I knew in marketing or production to gain leads on who to talk to for work. Luckily, my network already included the MAGFest crew, so that allowed me to connect with veteran voice actors and network with local gaming companies at conventions and events in our area. Being active in the theatre scene really helped associate me with my newly chosen vocation as well. Eventually, I came to be synonymous with voice over work, and I haven't looked back since.
If you're getting frustrated with bad ROI going the online route, turn your computer off and take a walk. Press some flesh, let the folks around know who you are, what you do, and how well you do it. And don't be afraid to ask for help! The community in your immediate vicinity should be the first and most important resource you have.