Clothes?

I've NEVER been fashion savvy. I have no idea how to find good clothing that fit me, I just wear secondary items from my family. How do you find a certain style? What do you recommend I do to find clothes that actually look good on me? Any stores you recommend? I'm aiming to look older. I'm currently 23, 5ft, and I look like I'm under 18. The Vans type clothing certainly doesn't help! It's hard for me to shop at places like Nordstrom because of my small size, so please recommend places that can accommodate my size!