This can depend a lot on the composition of the party, ages, races, classes, level, motivations, known allies, etc. The more you can tell us on all of those fronts, the better.

The idea that immediately struck my mind though is a coming of age ceremony. This gives a little bit of culture, allows them a chance to bond over a common goal, and gives opportunity to add an antagonist or two who are also apart of it, but may not want to work together as a team.