How do I only render specific objects? I have an orange juice splash in a jug. I want to render only the jug and juice in order to edit it in photoshop. Can you please help me how to do that?
I want to have all light and shading effects that the other objects may cause on the jug but without having the actual objects in the render. I don't want the floor and background either. 

Here is the scene rendered below, thanks.
Move all objects that you want to render in a separate layer.
Move all lights and anything affecting the objects in another separate layer.
Than click the second tab from your main editor (which says Render Layers). And select only the layers which you want to be rendered (the one which has the separated objects and the lights layer).