Tessellate.
Tessellate can really help you out if you want to add more faces/edges/polygons to your model. To Tessellate convert your model to and editable poly. and from the modifiers list select "Tessellate". you can also use "Tessellate" to smooth your editable poly too. If you put the Tessellation Tension. to 0 the modifier will not smooth your model. But if you do put in a number like 15 it will smooth your model. If you change the iterations of the Tessellate modifier you will have more polygons in your model.
Well there you go you can fool around with the Tessellation options to find which option is right for you.
1st image without tessellate modifier on.
2nd image with tessellate on tension: 0 iterations to 4.
3rd image with tessellate and tension set to 30. and iterations set to 4.
