I have most of my carded vintage by series (all the SW together, then ESB, etc.). Within the series I have them grouped by affiliation, so Luke and Leia are next to each other and my AT-AT Driver, TIE Pilot, and Snowtrooper are all together.
However, the far right of my wall is dedicated to the 6 bounty hunters, which breaks that rule as some are ESB and some are ROTJ. Just after that, I have six different stormtrooper cards because I like seeing the same figure across the different cards/offers/countries.