Pretty much straight forward task. In case it doesn't go without saying; shut the water off before you start. Should be valves on the incoming and outgoing on the top of the water heater, otherwise shut it off at the main. If no valves on the water heater, this might be a good time to install them. Only other thing I can think of is where the fitting was sweated on the copper piping, if that looks like it's corroded, this might be a good time to address that issue too.