Calling YA authors for your best marketing do's and dont's. (Sanity the #1 Goal; Sales the #2 Goal)

Before deciding whether to represent me, an agent has asked me to include in my proposal "specifically how you will leverage your platform to market the book. You may not have a lot of connections yet, but if you show me a stellar publicity plan, that can overcome a mediocre platform."

"Stellar publicity plan"? Help!

I do have all the basics—website, email list, newsletter, (small) social media presence.

This is for a debut novel--small town, mystery, spiritual coming-of-age, family, historical (1970s). As such, I won't be appealing to the rabid spec fiction readers that seem to dominate the market. But I will be appealing to classically educated homeschool teens (I think) and others with a more, shall we say, classical/literary bent. This part of the business has me running for cover--typical artist in a cave daunted by a million voices. So trying to develop the most effective marketing plan with the least amount of time. I already have enough gray hairs. I don't need more.

Best platforms for reaching your readers? (No TikTok for me.) Does an email list to teens get results? Or should it be to their parents? How did you build that specific list? Podcasts you recommend? Best use of advertising dollars? Connections? Resources? Your hard-won lessons? 

Genius is learning from others--so please teach this dummy. 😄  Thank you!