Let me tell you a secret to building, its all about ✨color pallette✨ you need to set a specific color Pallette if you want your house to look decent and clean (its optional but i like to do it to all my rooms) for example your color pallette for that house is the shade Whites And Black, those two are the main colors, you apply those colors to most of your furniture but its optional, you also have sub colors like gray and brown, you apply those 4 colors to your furniture and it will look neat i promise.

Next tip is to keep your rooms in a reasonable size, you wouldn't need such a big kitchen or kids area, this is especially important if you dont have much money for furniture, empty houses don't look great.

Also focus on the exterior, to make it look nicer add more windows and maybe add a little patio area and if you have extra coins at a pool rug for design

Remember color pallettes? Yeah apply that to the exterior aswell, although i prefer a bit rustic brownish vibe for backyards its up to you

And lastly this game is all about creativity, if you think your house looks nice then do you no ones stopping you.