(Higher-quality chocolate makes all the difference.)
Double-boiler method: Place the chocolate in a heat-proof bowl over a saucepan of simmering water. Make sure the bottom of the bowl doesn't touch the water. Stir occasionally with a heat-proof spatula until the chocolate is completely melted.
Microwave method: Melt the chocolate in 30-second bursts in the microwave. Stop microwaving when you see just a few small lumps of chocolate remaining. Stir until those lumps have melted completely.