Use your Management View to see where there's a need for either a Food, Drink or Shopping Amenity, then place the specific building in that area. When you're placing down a building, there should be a number indicating how many visitors the shop is likely to get. After you've built the Amenity, wait a little for the guests in the area to build up and actually visit the shop. Modules can quickly drain your money if you build them too fast, so wait for the guests to start visiting.
Once you have a nice build-up of guests, check your shop and see how many visitors it's getting, then see if you should build/change some Modules. If you hover over a new internal module it should tell you if it will increase or decrease how much money the shop will make.
Good luck, ARoc!