Due to the nature of tabletop RPGs, a campaign will often start with a random group of strangers. Here are some ways to get them adventuring together, without resorting to the old Tavern trope.
A man is taken in for a crime years ago. Any who ask or willing to listen, he tells a tale of how he ended up in such a position. So far fetched is the story that many believe it to be false. Perhaps the adventurer who came to town would like to listen to the man's tale?