This method is recommended by the New South Wales Oyster Foundation. A knife, oysters, and gloves if you are inexperienced, are all you need.
Note where the hinge is.
Rest oyster on a sturdy surface, flat side up, hold firmly, push knife through top shell opposite hinge end.
Press downward on the knife, levering top shell up. Separate top and bottom shells completely, then rinse them.
Insert knife under oyster, cut adductor muscle.
Lift oyster out of flat shell, place on the other half.
The smooth side of the oyster presents a more attractive appearance than the bearded side. (All opened oysters are turned over by hand before being sold.)