It largely depends on what you plan to use them for. My only advice would be to plug, wire, and fuse appropriately for the maximum intended use. You will also want to decide if you want them both on a single circuit, or on separate dedicated circuits.
If you are just trying to charge your phone or the like, you can probably get away with just tapping into an existing 12v accessory line. If you are looking to run an inverter, fan, or aux heater, then you might be better served to run a new line.