The key phrases here are, “where are the popular local markets?”, “which markets are best for souvenirs?” and “which markets will allow me to bargain?”
You want to find anything related to markets, night markets, weekend markets, etc. These markets are generally set up outdoors with stall after stall of random commodities.
Don’t act too interested. If shop owners know you like something, they’ll be less willing to negotiate down on price. They know that you’ll eventually cave if you show a lot of interest.
Ask the price and expect it to be at least double what they would offer a local. Yes, double (even triple, depending on the item and how interested you are).