This guide outlines the essential considerations for Managed Service Providers (MSPs) when selecting a Managed Security Operations Center (SOC) service. It begins by addressing the increasing sophistication of cyber threats that small to midsize enterprises face, emphasizing the need for MSPs to enhance their security offerings with managed SOC services. The document details key components that MSPs should evaluate, such as the importance of 24/7 real-time monitoring to reduce attacker dwell time, the necessity for comprehensive threat vector visibility, and the need for simplified alerts that map to the MITRE ATT&CK framework. Additionally, it discusses the integration of managed SOC services with existing IT and security tools to improve operational efficiency. The guide also highlights the value of proactive threat hunting and actionable threat intelligence, which are critical for identifying and mitigating potential threats. Finally, it addresses the cost-effectiveness of managed SOC services in the context of MSP business models.