Select your object and reaset X-form. This step is really jsut a precaution. If you used the mirror tool or 2D scaled your object you will be left with dirty transform numbers. If this is the case you will get black dots or strange ugly lines in your render.Your UVs must have a couple pixels spacing. (or you will get colour bleeding)

I like to give the object a slightly shiny matirial with a low glossiness.