I think you could develop a sense of fashion from reading fashion magazines? Though u may not be interested or think high fashion (e. g. vogue/ elle) are a bit too much to carry and afford, u start to get the sense when u read more. If u don't want to spend money, there's plenty of fashion blog on the internet, the one I really like is "Lookbook. nu"? Its always shows all the fashion bloggers around the world, so u could follow the ones u like :)
What do you like? What celebrity's style do you like to see and in which clothing do you currently feel comfortable in? What fashion era do you most like? When you factor all of these things in, you'll get your style.