To have a cool outfit, you don't have to follow everyone else and focus on what they're wearing...yet saying that, you can be inspired to create your own. Usually the coolest outfits or when people say "Wow she looks cool", is when the outfit is completely out there and different to everyone else.
It's good to be inspired by other people's style as you can see what's trending at the moment and learn how to wear it. The only thing you should be careful of and remember, is to still create your own style that's unique to you. If it's hipster, urban, chilled, funky or moody... whatever suits you is what you should be aiming for.