Marissa's and JoLynda's suggestions are great!
I would add:
Check out a podcast called The Voice Experience
Get 'voice over' and acting training or coaching
Practice reading out loud and recording it on your phone - short pieces at first (1-2pgs) and go over the same pieces adjusting your tone, timing,
Seek out pro bono gigs to build your resume - for example, record the intro/outro for friend's podcasts, YouTube videos and ask if you can use in your portfolio
Build a portfolio of several voice-over demos - of those intros/outros and practice samples that show your range
As with everything build your professional brand online
Look for auditions and audition often - search: voice over auditions, voice over open calls, voice actor auditions/open calls
And check out the industry's professional association, the World-Voices Organization (WoVO) is a non-profit, member-driven international association of voice actors, https://www.world-voices.org/
Reach out to them about a student membership, while not displayed on their site most associations have a student or temporary membership fee and ask about mentorship/apprenticeship. Start networking or following board members and past conference presenters for insider information on industry trends and direction.
I know several actors who have also booked jobs in voice acting. As with most things in the entertainment industry, it's all about making connections. I agree with Marisa. Take acting classes, get on the radar of Central Casting to at least start going out for regular side jobs so casting directors get to know you, and check out Audible. They are always looking for narrators and voice actors on https://www.thevoicerealm.com/. You can become a self-registered kind of actor. Not sure how viable this is, but it is out there to use.
Even better, I've seen this posted on my Audible membership page several times:
Voice Talent - If you're interested in becoming an audiobook narrator, please email email@example.com and include: Two-minute MP3 clip of your audiobook narration (i.e., not commercials or radio demos) List of books you've narrated, if any. Indicate which, if any, are being sold on Audible.com.
Here's the link for that: https://www.audible.com/ep/business-inquiries
I'm not a voice actor, but my husband is an actor and we talk a lot about the industry. First of all, it's really tough to break into voice acting. Not to say it's not worth it, but it's a very small community and a lot of work to actually make a living off of. I would recommend building up your network, for example, sign up for classes at a reputable acting school, talk to the teachers there and see if they know voice casting directors or specialists. Invest in a good sound system and create sound reels so people can hear what you can do.
Marisa recommends the following next steps: