organic natural pesticides snails caterpillers instect repelant

Hey
I've got a few outdoors just starting off growing and I've been having some serious snail problems and I've also seen a bunch of caterpillars around..
so im worried about them too..

i want to keep the plants organic and natural but still keep the bugs away!!!

ive tried eggshells for snails, which sort of helps but you have to use heaaappsss

and ive heard of using tobacco?? any information about this, think it would give a nice taste too......

ps:and if any one else is in the bottom half of australia their advice would be valuable o'''