Casting setups are one of those things that grow as you go. You start with enough to get your feet wet and get you through a few pours and then you find yourself collecting all sorts of objects, molds and things to try more. Back in 2008 I decided I just wanted to make myself a few blanks to turn and it's now my full time job. Lol.
If yiu Start small, get to know your resin and tools, keep it simple, and keep notes, you'll do just fine.
If you're available in April to attend the MPG in IL, you should check it out. We always have several demos on casting and there are plenty of people there, who do it, to ask questions.