Throughout the centuries the role of fashion has changed because of people's mentality that was influenced by history, by the changes it involved. In the past, men and women reacted differently to these style changes but now both parts are attracted by fashion in the same way, as they generally think it is important to follow it. In my opinion there is an exaggeration in understanding what it is all about clothes and accessories, what is new and has to be adopted by us.
First of all, you can't dress as you'd like in any circumstances, as you are at school or you have a job that involves seriousness, and if this misses it can affect your own career. For instance, if somebody is not dressed decently at school, this can influence the teacher's opinion about the quality of his/her answers (even if the teacher isn't aware of that) and it can affect the mark that he/she should get. On the other hand you can be dressed decently but also follow the fashion because fashion doesn't mean that you have to wear exactly what you see on TV. For example you can use the same colours on a decent dress, I mean that you can take from what is "fashion" only what really fits you.
Secondly, one of the most important things is to adapt your clothes to your own personality. This can be connected to the way you dress reflecting your purposes in life or at the moment. For example, if you are a sportive type and you work in a place where you have to be dressed elegantly, you have to find a solution of compromise because you can look ridiculous when you wear an elegant deux-pieces and high-heeled shoes.
Thirdly, you should also think about your own possibilities to spend a lot of money for jewelry or clothes.
In contrast, there are some people who really need to show that they follow fashion and these ones are stars and officials, the people that appear and interract on TV. They are supposed to give us an example of dressing with taste. Besides that, they can afford to spend more money because this helps their image be better sold in the stars' marker.
Considering these points of view, I would say that fashion has three values that influence you to follow it or not: money, personality and purpose. Needless to say that the most important thing to think about is adaptation.