Which Book Marketing Agency Actually Helps Authors Reach Readers

Hi everyone, I have been looking into different book marketing agency options, but it’s hard to know which ones truly make an impact. Some authors swear by social media campaigns, while others focus on email outreach or connecting with reader communities. I am curious what book marketing strategies or agencies have genuinely worked for you? I’d love to hear honest experiences, tips, and advice from anyone who has tried different agencies and seen real results promoting their book.