Agentic AI systems represent the next evolution of artificial intelligence, enabling reasoning, decision-making, and autonomous action in dynamic environments. This paper serves as a practitioner’s guide for system designers, developers, and computing educators seeking to rapidly adapt to this paradigm shift, which will require adopting an agentic AI mindset to harness the full potential of autonomy and automation. Core concepts like the reason-then-act (ReAct) model and a conceptual layered agent design are combined with the latest guidance on communication and orchestration architectures, agentic AI design patterns, and practices for adapting the validation and verification process to the unique challenges of agentic AI systems. Practical steps are outlined to cultivate the agentic AI mindset across industries and academia, and open-source enablers are highlighted to foster accelerated adoption of agentic AI technology. This quick start guide provides a solid foundation for developing robust, scalable, and effective agentic AI systems without overlooking the importance of appropriate governance.