When I was living in Rishikesh last year, in the district Tapovan where you find many of the yoga schools and ashrams, the commonest sight outside of the many sadhus – the wandering Indian holy men – was foreign people wearing different kinds of eastern raiment indicative of their spiritual pursuits, commonly white flowing cotton or saffron coloured cloth, often with the sorts of prayer beads called mala in this part of the world. Head cloths, coloured sashes and so on were also part of the look.
The commonest response for someone when they undertake a new activity or sign up for a course of some sort is to wear different clothing to tell themselves that they are committed to that pathway or course; that they have, or are engaged in a process of changing their identity. It makes them feel different and also serves the purpose of showing other people ‘out there’ that they have become spiritual devotees or one sort or another. These are simply devices to mark a change within the individual psyche, like wearing a uniform, but they are in no way necessary to the successful pursuit of the pathway. In Yoga traditions employing Zen like methods, the need to define oneself by wearing particular clothing is simply another form of identity making or conditioning. You are not in the process of deconstructing the various former identities that have defined you in the past, but are simply acquiring another Russian doll style container for this new stage of life.
My personal belief is that it doesn’t really matter what you wear, as long as you are quite clear what purpose you are serving, what it means for you personally and why you feel it important to progressing your pathway to wear or not wear certain sorts of outfits. To dress in Eastern style clothing and adopt other practices simply to conform to an image consistent with what is generally viewed as being a yogi/ni (practitioner of yoga) will have achieved nothing except to deepen the darkness one is purportedly committed to dispelling. You will become a yogi/ni by applying yourself with diligence to the work required to be done, not by donning an outfit.
Being clear always about the reasons why you are doing whatever you do, is the essential first stage to embarking upon this journey of enlightenment. Adopting behaviours or cultivating self images in order to conform to some outer worldly notions of the acceptable or the fashionable will also only serve to bind us to that world, whatever sort of world it might be.