When you use the Layer Styles panel to create a drop shadow, you usually get a flat-looking shadow that makes your object look as if it were floating right above the surface of the layer behind it.
Two things you can do to create more realistic shadows are, to first select a color that matches the other shadows in the scene (instead of just black).
After applying the Drop shadow from the Layer Styles panel as you normally would, right-click on the word “Effects” in the Layers panel, and select “Create Layer“. This will remove the layer style and create a new pixel layer that contains the drop shadow.
You can then press Ctrl (Mac: Command) T to transform it and match the perspective of your scene.