You maybe want to decide if you want to pour or inject first. I inject and wouldn't even consider pouring baits. The quaality seen in injcted baits is way over the top of the best hand poured.

Next maybe decide what kind of baits you plan to mold....pannies?, bass?. Bass will slaughter softer baits so a medium plastic is maybe what you want to begin with if bass are on your mind. Crappies and panfish get all soft plastic in my molds and I even add softener to the soft formula. I use only Caney Creek's pthalate-free plastic. Plastic in smaller quantities will bite you in the butt cost-wise, but get a quart of each of medium and soft to see which one suits you best, then get the 2.5 gallon container in your preferred plastic.