The good ol’ fashioned “You all meet in a tavern, answering a poster offering gold for help…”? The action-scene, “You’re all engaged in mutual mundane task, when suddenly a band of thugs/goblins/whatever bust in looking for the plot coupon and chaos breaks out”? The “Elder Scrolls classic” - all being prisoners thrown in together? Tie it in to a character’s backstory and let them lead the other party members in?
What have you found interesting or successful, and why?
Really depends on the general theme of the campaign imo :3
Taverns are a good set up for a mercenary style campaign, getting ambushed and having to work together sets up a nice destiny plot, meeting at a town by happenstance sets up a nice mishmashed family all traveling for their own goals, but finding it helpful to stick together etc.
See, this answer I like because you actually differentiate by the style of campaign. I’ll definitely take this advice under consideration!