Human Augmentation Technologies (HAT) are rapidly advancing, promising to extend physical, sensory, and cognitive capabilities. However, their development often remains technology-driven, overlooking the human, social, and ethical dimensions critical to real-world integration. This paper argues for a Human Centred Design approach to HAT, one that foregrounds lived experience, contextual awareness, and inclusive participation. Through a review of the current HAT landscape and a case study of the Second Skin project, which engaged manual workers in the co-design of a wearable augmentation prototype, the paper demonstrates how embodied, participatory methods can reveal user insights and challenge dominant narratives around efficiency and surveillance. Building on this foundation, the paper proposes a set of design principles tailored to the complex demands of augmentation emphasising empathy, ethical reflection, adaptability, and systemic awareness. By reorienting design processes around human values and societal context, this work contributes to shaping augmentation futures that are not only innovative but also equitable, sustainable, and attuned to the realities of those they aim to serve.