What Zachary_Brackin said.
Here is a link to the Micro Mesh NC-78-1 restoring kit that I used. It is not cheap, but it gives great results and contains grit ratings that I had never seen before.
Here is a link to a video that shows the process and finish you can get with their kit of ultra-fine sandpapers.
Also, whatever program you are using to create your curved models, make sure that you view them in 'flat' mode, as that is what your print will actually look like. 3D programs usually mathematically smooth out the appearance of the model for rendering, but that does not affect the geometry, which is what PreForm will be printing from.
Organic shapes need a lot of triangles, so I subdivide my surfaces until there is no visible faceting when I zoom right in. That way the model prints very smooth, but with a slightly dull finish after curing. The micro meshes kit brings out the shine.
I spend a lot of time on finishing as I make a mold from the print. I can then create many copies, quickly.