Really depends on how you want the map to feel like:
Something large with many buildings and places to go that require traversing the map.
Something more compact that has most of the sellers by places where you use them.
If you go with option 1,try making a map that players have to memorize the locations within (if you don’t have a minimap).People will have to go to those locations to get whatever they need,and will return to the place where they use what they got.
If you go with option 2 however,you have to get good placement of locations.For example you would have the Police station near the Mayor’s house, or perhaps the Gun smith next to the Bank.
Either options,it’s important to know that these locations should make sense to the people living on the map.It’s not just for players to go to.
I believe if you want to make a game, you have to plan out the map before going into Studio. Lets say i’m making a western game. I have to think about a big region with lots of stuff in it. But, i’m stuck in this specific place. If theres a popular western game out there, i would take inspiration from that. Or something around my city and whatnot.
Okay, before making the map, make sure you get the actual gameplay in a working state. That way, you can make changes to your map idea after everything is ready.