This paper discusses the user and technical requirements in designing smart garments for biomedical monitoring in several and very different applications: in hospital settings, during activities of daily living (ADL), sport and fitness, home care, working environments. Anthropometric and gender considerations are to be included into design as well as textile requirements like elasticity, washability and chemical agents effects for preserving sensors' efficacy and reliability, and assuring the proper duration of the product for the complete life cycle. Physiological issues are mainly due to skin conductance (and related operations: cleaning, scrubbing the external layer of dead skin cells, the presence of hair - especially in male subjects), skin tolerance and irritation, and the effect of sweat and perspiration. All these factors strongly affect the design and technical choices (materials in particular) but aesthetical requirements are proved to be crucial as well as comfort and wearability. For this aspect, user's age, target application, and fashion trend could not be ignored, because they determine the final success of the wearable monitoring approach.