What you wear says a lot about you. If you wear punk clothing, you may be seen as a rebel who doesn't care about fitting in. If you wear jeans and a t-shirt, you may be seen as laid back and unassuming when you go out in public. Those who wear clothes that have stains on them or have holes in them may be seen as lazy or not willing to give up their favorite shirt or pair of shorts even though it is time to do so.
It is important to know what you can and cannot wear in certain situations. For example, if you show up to a job interview in casual clothing, you may not be seen as a professional. That could make it less likely that you get the high paying job that you were hoping to get. However, if the interviewer tells you to wear casual clothing to an interview, you wear casual clothing to the interview.
When you dress yourself, you want to make sure that you are comfortable first and foremost. Once you have found something comfortable to wear, then you want to make sure that it is stylish enough to make a statement about who you are and what you represent.