If you're not in the booth recording, you should be marketing or looking for work. You say, "Easier said than done, John." Well, it sure is a lot easier to search for voice over jobs today than it was years ago for one simple reason. The Internet.
I tend to get hired to do corporate video narrations or e Learning projects. So, going to a search engine such as Google and inputting "Corporate video production" should bring up many production companies who may have need for voice over. On the home page you will often see an "About" heading which may well contain the name of the founder,production director, or man/woman in charge. I use email marketing a lot. I know social media can be great for marketing efforts and getting the word out that you exist, but I have found emailing directly to still be effective. You want to get a first name of someone at the company so you can include that in your greeting. I just sent out some emails to corporate video companies and one man got back to me and said he read my email because, unlike spammers, I actually referred to him by his first name. He said those without his name get deleted. Always try to personalize the email with his/her first name! And make your email very brief. There may be a temptation to go on and on about what a wonderful voice over talent you are, but opt for brevity. The people you'll be contacting are more than likely busy and have very limited time (as in seconds) to read your email.
I have actually had folks email me back the same day I sent out my marketing email and say "Good timing. We're working on a job that's going to need voice over." You can then offer to record a short audio sample using a bit of their copy. A sort of audition. Sometimes you'll send out marketing emails and you won't hear a thing right away. I always say email marketing is like planting seeds. It may take a while for them to sprout. And the subject line of the email is very important. Experiment with different ones. I have a variety I use. I built my voice over business around good voice over and fast turnaround. I often use "Same day voice overs" in the subject line. Your subject line matters- a lot. Your goal is to get the email opened and read.
As creatives, our joy comes from hopping in the booth and recording voice overs and then getting paid to do something we love. But you must learn to wear a lot of hats in this business. If you hate marketing, consider hiring someone competent to help you. Without consistent marketing, your voice over business may well die on the vine no matter how talented you are. There are many other ways to market your voice over business beyond emailing. But it's still an effective way to get new business. And inexpensive.