Highlighting, and shading - Halfway Done.
At this point you should have used the cube you drew as a guide to remove excess parts of the tomato.
Partially remove the existent highlighting with the healing brush tool. Notice that I have removed most of the large circular highlight which used to cover a part of the tomato, and replaced it with more subtle, sharper corner lightning.
Select a soft brush with a very low opacity to start highlighting the tomato using the cube that you drew as a guide. Build up the highlights slowly for best results remember that certain areas such as corners need to be more glossy than the edges.
Finishing up
Make a new layer and set the layer mode to overlay, this new layer will be used to give the tomato a more natural look.
Pick an imaginary light source and start shading in areas that you want to be highlighted with a soft brush. The areas you shade-in will become brighter, than the rest of the tomato and provide an illusion of light.
Finally you may optionally add some faint noise for realism.
