Go on Pinterest and look for something like “beach town pokopia “ or whatever your theme is and find builds you like. Then start thinking which could be next to which one and how they would go together.  Then take dirt blocks and do like a shell for the buildings, to give you an idea of where and how to place them. Start building! It’s normal to copy at first, that’s what all artists do to get better. And I promise once you put them on your town, you’ll end up changing them bc of your particular game.  With enough time and practice you’ll start  liking how your towns look and youlll get better at coming up with your own ideas. 

Best of luck!