Despite that many consider the wearable technology as an emerging field, researchers in the field of Human-Computer Interaction have already done and published a lot on the topic. As a result some key usability concepts have been established, providing guidance to designers of wearable products such as the term wearability, the design for eyes-free interaction, the provision of multmodal feedback and the appropriateness of gestures to flexible surfaces. By following these rules one is much more likely to succeed in his quest not only to design a beautifully looking product, but also one that delivers a great user experience to its wearer. The talk will conclude with a short discussion about two wearable devices designed by the speaker: FabriTouch - a textile touch input surface embedded in one's trousers and Stepsss - the smart shoe layer that tracks your running and walking behavior.