This is the entry level mold you should be attempting if you want to get into casting skulls for your haunting needs. It's cheaper than a jacket/matrix mold and much easier to build. It's gonna cost you about $80 total plus the casting material but you get 40+ castings from it and learn something new.
These are two long videos but they show you every step. I always find it helpful to see the whole process myself.
If you have questions post them in comments and I'll answer them.