Make sure your PSU can handle the new card and has the required connectors, that is about all the preparation you need. Otherwise you can basically swap them willy nilly, the driver stuff can be done after the card is installed.
Uninstall old drivers, clean it all up so there's nothing left behind.
Download new drivers and have them ready.
Turn off the comp, take out the old card, put in the new one.
Start up, install new drivers.
Done.