I've only just begun molding and casting, mainly various headsculpts, but have learned a lot already. Not only by actually doing it, but also from experienced casters (props to Clonehead!). I don't know if it's beginner's luck or skill, but immediately my first few attempts produced some very nice results. I only have a few tiny air pockets, mostly in horns and such.
I think molding/casting is one of those techniques you need to study carefully before jumping in. It's expensive and with every failed attempt you just hear your wallet screaming in agony
If you mess up a paint job, you can easily start over again. If you mess up a couple of casts, or molds your casting/molding materials are gone.
I'm really looking forward to the rountable and quite honoured to be part of it.