When I was younger I didnt have alot of money to buy the things I thought looked good. I always liked clothes - I liked the idea of exuding a statement without saying anything - so when I finally started to make a little money and began buying clothes, there was just no stopping me.
The first step I think is finding what style(s) you like. The second and most important IMO, is finding what compliments your body. For example, I have a long neck. For me, almost any shirt with a collar looks better than one without. So if I see something I like on the rack or even on someone else, I first try to decide what about the garment I like, and then think if ultimately it will look good on me based on its fit and my body. If it doesnt, I simply make a mental note of what I liked about it and find something else similar that better suits my body.