Social media in marketing YA?

How effective have you found social media in marketing, specifically to a YA audience?

I have two published books, but am relatively new to marketing. I’ve had an email newsletter for a year (started with 17 subscribers, now at 100) and a website for 9 months. I know I need to increase my platform, but I’m not really sure how… so I’m thinking about trying social media.

I currently only have a personal Facebook account, which I’ve occasionally used for marketing (since my FB friends are mostly my mom’s friends who are delighted to buy my books), but that’s not ideal for reaching a YA audience. But I never used social media as a teen (I’m 19 now), and very few of my friends did… so I’m not really sure what’s popular or effective marketing to a YA audience (or if social media is even effective at all).

Anyway, I am grateful for any thoughts on that!