Some background: I am a relatively new GM (though fairly experienced player) and something I'm really having trouble with is integrating the back stories of my players into a central story line without doing something cheesy like "you all meet in a bar in place X, spend the night drinking together, and become great friends". I would appreciate anything- general tactics or specific examples, whatever you can think of. Everything is appreciated!
Some information that may help (character basic summaries and basic party info):
The campaign has not yet started, and as such the party consists of 4 players, all level one with no experience.
player #1) A highly charismatic rogue, born and abandoned by his parents, he was an abused orphan. Eventually he learned to use his good looks to get most of what he wanted, and stole everything else. CN
player #2) A samurai driven purely by revenge. His wife-to-be was slain by the Red Mantis Assassins and now he seeks only to eliminate any and all Red Mantis Assassins. (He's Ronin, of course)CN
player #3) A ninja descended from a long line of fighters who shun him for choosing to follow what they view as a disgrace to their family line, sneaking around in the art of stealth and what they perceive as "evil". He wants only to prove himself worthy of his families admiration. True N
player #4) A sacred shield paladin. Very standard paladin back story, she received a vision from her god (Erastil) to go out and hunt evil wherever she might find it.
Thank you in advance for the help everyone!