Strategies for Generating Leads for Asset Management Firms

hey guys, hope you had a fantastic christmas break! one of my clients is an asset management firm for startups and entrepreneurs. they essentially trade on behalf of their clients making them 12-18% profit on what they invest every single month (pretty astonishing to be honest, I only believe them because they did it for me as well) They have 150+ happy clients (from startups to VCs, real estate agents, lawyers etc) and have generated like 1.3M + in profit overall I’m stuck on how to get decent leads through outbound - how can I find decent leads without relying on Apollo? None of my campaigns seem to work well Also, how would you recommend I use prompts to effectively get the message across?