Personally I'll just avoid your question for now. I'd suggest immersing yourself in the likes of Sephora, then Higher end dept stores (Saks, Barneys, Neimen's, etc), and then boutiques like Bond #9 and Creed, then even more niche stores like Aedes De Venustas (in that order),
and after a long long time of getting your nose educated, then go to some of those random shops. You'll already know what you like and don't, and will know what you want to buy and what the prices should be, and if they're real/fake or old, etc. But I'd suggest first starting with the best stuff so you see what it's meant to be like, and you get knowledgeable helpful customer service.