Well first off have you read any science fiction novels based around that concept?
Might want to try some Elizabeth Moon books or watch Firefly since technically that is somewhat of a traders game albeit more edge inclined than Lando Calrisssian's latest gambit...
Secondly have your players designg their characters and spend the first session (or two) dealing with their background explaining how they met whose ship is it anyway and why they're working aboard her.
The trading part can serve as an ongoing subplot but if you're using Edge thats all it should be it serves to keep the story going not the whole point of your campaign.
For example we have the ship captain a former Marine who mustered out following a cataclysmic battle where the Empire overwhelmed his home. Unwilling to stick around and play ball with those who killed and maybe murdered practically everyone he grew up with he chose the life of a trader to try and make ends meet and hopefully one day come to terms with the dreadful memories of his past.
His second in command is also another veteran and served as his second during the war and was able to remain sane because she relied on her co whose now the ship captain... she operates as head of security aboard the ship making sure everyone's safe and the ship's crew out of trouble.
She married the ship's pilot who joined shortly after they bought the ship he married the security officer and stayed simply because he liked the ship and most of the crew... not all mind you but the ship's captain is a good man and in a universe where there's either the Hutts, Black Sun or doublecrossing thugs all looking for their chance thats a rare quality indeed!
The baby of the crew is also the ship's engineer, she's the product of generations of spaceship crews as well as traders and has works miracles with the ship having replaced the original engineer who turned out to be disinclined towards the ship's wellbeing.
Pretty much treated as the daughter of most of the rest of the crew she has a crush on one of the two new crew members' even though he held her life as hostage to protect his sister a force sensitive being hunted by the Empire.
The muscle of the crew is a former bounty hunter who changed sides because the ship's captain realised his self interest was mixed with a similar need for stability and security he could provide (read decent food, a room of his own and decent pay for usually alot less danger than he was accustomed to) he's actually better natured but still a little too mercenary for his own good used on a couple of occasions to put the crew in danger albeit he balked at outright betraying them so far.
It also helps he has a crush on the engineer, but is genuinely scared of the doctor's sister for good reason!
The diplomat is ahem using the ship as her personal ship so she can complete tasks assigned to her since she's often called a companion and other very rude things but out here in the Rim she represents one of the few forms of stable organisations everyone respects. The fact she is secretly a member of the Rebel Alliance and using her feminine charms to accomplish her intelligence missions is something the rest of the crew are totally unaware of...
The three newest members of the crew include two siblings one a practitioning doctor and his sister whose on the run from the Empire after he broke her out of their Rehabilitation Camps where they were training her as some kind of Emperor's Hand so keeping a low profile on a ship out in the Outer Rim sounds like a good plan until they can find a safe world to disembark the ship and disappear... the good doctor isn't a problem he's actually very useful and as long as his sister isn't threatened is a good influence...
His sister how is force sensitive and unstable thanks to the Empire's tender mercies and apt to demonstrating that she can read minds and people demonstrating alarming combat skills and a habit of threatening the mercenary for kicks... well okay that was after he tried to sell her out to the Empire and they tried to doublecross him as a result but still he was provoked!
The third is an aging preacher belonging to an obscure order of monks that grew up after the Clone Wars.
He's former Imperial but of a good sort apparently seeking to do good work before he passes on and signed on with this ship after talking with the engineer and continued after the debacle with the doctor's sister apparently having experience dealing with force sensitive people and evidence suggests he killed a few of them himself...
Maybe I ought to have focused on the trading side but i hope this helped!
Edited by copperbell, 27 April 2014 - 04:24 AM.