What is the Most Effective Way to Promote a Book Today

Hi everyone, I am an author trying to get my latest book noticed and I am exploring different book promotion services. There are so many options out there social media campaigns, email marketing, influencer shoutouts, and more—but I am not sure which ones really make a difference. Have you tried any strategies or services that actually helped your book reach more readers? I would love to hear your honest suggestions and experiences.