With rocks and driftwood boil, boil, boil, boil. Plants aren't so easy but from now on I will be soaking all new plants I get in "Snail rid". In fact the plants I have will be soaked before hitting my fish room (once it's finished). With fish it never hurts to quarantine when you first get them.
Edited to add: If getting fish from the wild you should ALWAYS quarantine and a quick salt bath may help reduce the chance of introducing external parasites into your tanks.