Voiceover forums on Facebook and Linkedin can be a decent place to start when you're considering a voiceover career but they are not a replacement for voiceover training. Some talents tend to get too comfortable participating in dozens of these groups daily. It's like working in a corporate office and spending too much time going from cubicle to cubicle socializing. It's a time suck and can become quite the distraction.
You'll find plenty of good information in VO forums, but some of the advice can be misleading. These days, everyone is a guru on social media no matter their experience. Everyone wants to help! If you're passionate about learning the business, too many visits to the wrong group can spin you out! Stick to groups that are moderated by seasoned professionals.