non-symmetrical mold design

Hi.  I am trying to make a 2 piece mold from a part and am having trouble figuring out how to use the "split tooling" feature.  I have made simple mold for symmetrical parts before but this has me scratching my head.  I think my first step would be in making a parting surface but i dont know wether or not to include all surfaces of the part or not.  Any thoughts or ideas would be greatly appreciated!

SolidworksPlastics And Mold Design