I'd love to learn from any folks here who are also authors about best practices / efforts for book sales. Have a book releasing soon and any insights appreciated for this first-time author. Where did you see your best ROI? What were the mktg / promo / publicity efforts that worked or failed? Thank you for any and all advice!

I am looking to get brand ambassadors who are backpackers for my platform Hostelmatch - aggregator for hostels. I am looking for these brand ambassadors to hop around hostels promoting the brand and create content while they do so. I am struggling to find travelers with micro following who want to create content and promote the brand. Any suggestion on how I should go about with it and get these backpackers?