Voyages of the Dawn Trader
This seems like a good place for putting rules related information regarding the campaign.
This campaign will not be part of any of the published campaign settings, but borrowing liberally from Eberron fits the setting (and a little Forgotten Realms, maybe). To represent the background, some of the magi-tech of the setting would nicely represent the superior tech of the Principalities. Rather than create the other nations from whole cloth, I will likely pull the character (if not the geography) of the major players from the Eberron campaign.
It’s a good idea to read the Historical Background before creating a character.
The racial makeup of the world is very diverse (the Sage Kings each had a “favorite” race, but they employed or meddled with them all), but if you want to play a race too far from the “classic” races (human, elf, halfling, dwarf), be prepared to write up a bit of how your race fits in with the Historical Background and with the Principalities. Genasi and Warforged would be good fits for more unusual characters and both could be legacies of Sage King meddling with the forces of nature.
Just about any class should work, though some might be an odder fit (Monk, Shaman and Barbarian come to mind..). All of the old standards should work. A swordmage or artificer would be a characterful addition to the party. The Principalities are not particularly devout compared to their more dogmatic neighbors, so be prepared to write up the role of religion in the Principalites if that’s your character concept.
One thing to keep in mind when conceiving of your character: metal armor sinks. This would be a good campaign to wear light or no armor.
Organizations and Patronage
The Principalities are a collection of diverse interests: the Guilds, the Princes, the Navy, esoteric brother(and sister)hoods, etc. Each player is encouraged to flesh out the organizations to which they have loyalties or obligations to.
Roman-style patronage is a part of life in the Principalities. Wealthy citizens are expected to provide guidance and support for “clients”, followers that are part dependent, part constituency. Status in society is in part determined by the status and number of your clients and your patrons. Each player is encouraged to flesh out the identity of a patron and possibly a client or two.
These relationships should inform the character’s motives for joining Prince Marco’s expedition, and define some of what they hope to achieve from it.