RECORD A DEMO.
Nothing gets me more miffed than getting a pm that says, "can I VO plz XD", but they don't have anything to show. Record some sample lines with a diverse range of emotions, and you'll be golden. Just keep in mind that if you approach animators, you need to start by showing them what you got.
BlueAlpha14
There is a Voice Acting forum section on Newgrounds. Mostly people put help ads for voice actors. To be honest that's the only way you're going to find VA work on NG unless you become well-known and people hire you. If I had a decent microphone, I'd probably take it up myself.
aggimajera
Hopefully you can at some point. Thank you!