Welcome to basically any creative industry!
All the jobs seem appealing, so there is a HUGE amount of competition, which means only the talented, dedicated, and lucky, will find success. Whether its acting, music, art, or being an athlete, it's basically the same story. There's a massive pool of hopeful prospects, and only the cream of the crop will find much success.
I'm a professional actor and I've done a little bit of voice work, but not much. Here's my advice; practice, practice, practice. Get good. Do this first. There is no point trying to get anywhere if you're not good, or at least able to do the job. Because there are many, many people out there who ARE good already, so why would you ever get the job before them of your not good too?
To get good at voice work, you need to develop your voice. Do vocal exercises every day. Work on your breath control, vocal dexterity (diction) and your tone control (pitch etc). Accent work would probably be a good idea too. It would also help to take some acting lessons. After all, you're still acting, but only using your voice to convey everything, which you could argue is actually harder. You should also practice reading things aloud from a script. This will be very important for commercial work, which is the majority of the work available for voice artists. Sure, everyone wants to be voicing animated films etc, but you'll probably be auditioning for more toothpaste ads than actual acting jobs. Especially at first.
Then, once you feel like you have some skills to offer, approach some voice acting agents. There's plenty of them out there. They'll probably want you to record a show reel so they can hear what you're good at and so they can put you forward for jobs and try to get you auditions.
If you get an agent, then you'll start auditioning and you've officially begun... At the very bottom of the ladder. And in order to climb you just need to keep working on your skills, try to make connections, keep an eye out for work (even if it's unpaid at first), and just persevere.
It can be daunting and tempting to give up, but literally the only way to succeed is to keep going. So you do. After all, SOMEONE is going to get that work.. And it could be you.