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 a 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.