A question about the Smooth on starter kit

So I just got the Smooth-on brushable starter kit, and I was wondering if I should follow the instruction book to the best of my ability, or if there's anything I should do differently to have a better mold outcome.

For example, do I need to do all 4 layers? Do I need the cut seam? What about keys?

Any other advice would be greatly appreciated. I don't want to screw this up. I've spent so much money on this project and I really, really want to get it right the first time.

Thanks for looking! (: