If you are planning on going to a new country or new place whether for exchange or whatever it is for, I recommend going as yourself. No matter where you are going, you are the best person you could go as. I wouldn't go to extraordinary lengths to change myself, if I were you. If your hair is a bright purple for example, and you feel that that expresses you well, then I think you really should not worry too much. Once you get to your destination you can decide whether or not to continue dying your hair, or wearing a certain style, or whatever it might be. I think it is just most important that you go as yourself. If you are worried, don't be. You will be liked for you. Why be anything other than you, anyways? It is exhausting, and that is the last thing anyone needs when they are already going to be tired from being immersed in a new culture. That's not to say that say you shouldn't push yourself to try and do new things once you are at your destination - just that you shouldn't feel like you have to be different.
If you don't know who you are, like it seems like so many people don't these days (sometimes I wonder if anyone can truly know who they are - there are just so many aspects to consider, that a person can't be simplified down to one thing), present yourself as naturally as you can. Use this opportunity of your time in another country to explore yourself and figure out who you are. There is likely no better time or opportunity to do so.
This is probably going to seem like extremely pessimistic advice, but think of the worst thing that could happen. Now find a positive that you could have in that situation, and get excited about it. Doing this really helped me. I was worried that I would come to Germany and not get to know anyone, not make any friends or acquaintances, just being alone in Germany, since I am generally a quiet person when I first meet people - which I am fine with being. But I love to read, I love to write, I love to think. And I found my positive through this. I realized that no matter what, I can always go to a cafe or something of the sorts on the weekends, or go sight-seeing and see the history that is in the everyday life here. I got excited at any possibility, I got excited for this possibility, and others. And now that it is turning out to be more than that, better than that, I can only be happy. I prepared myself for the worst, made myself excited for it, and in result, I am all the happier for it now that I am here.
I hope that this post is of use to someone, I just suddenly felt the need to do so, despite just putting up my other post.
I hope you are all doing well, see you soon!