How do you have your group meet, besides the age old, tried and true method of, "You all meet in a tavern"?
I run a lot of one-shot adventures. My approach is to tell them they've already met. I say: "You guys are the official group of adventurers for this village, you've been working together for a couple of years, you guys are all friends and you trust each other. Nobody's going to do anything like backstab your allies, steal loot from the group, or betray the group to a villain for the lulz."
This cuts out a lot of the intergroup drama and lets us move straight to the adventure.
I've tried (and seen other DMs try) other approaches, like just narrate that everyone is in the same place and expect them to make up reasons to form a group.
I've never liked this approach, because it always feels artificial.
One player character is an elf wizard who's racist against dwarves, one player character is a dwarf who hates all wizards, one player character is a thief who's obviously out to steal from everyone else; why are these people deciding to trust one another with their lives? The players can always feel that it's awkward and artificial, but they have to do it anyway.
I have found that it's better to skip the forming-a-group step and tell them they're already friends.
The technique I find works best in most genres is to inform the characters that they already know each other before they even create their characters. When I expect detailed stories and time is abundant, I often tell them to collaborate in their stories to arrange for some sort of shared history before the game begins.
An NPC introduces them
The first quest-giver can also call them all together and inform them that they will be working together on this particular mission. This fits a little less well with the "Sandbox" ethos than some might like, but most groups I have played in, even the ones that prefer sandboxes, tend to accept this particular conceit fairly well since it gets the ball rolling as it were.
I think this also has a great deal of verisimilitude since it is often the employer that assembles the team, at least initially, in the real world and you will find similar concepts constantly in fiction.
Consider the Campaign
When choosing the way to introduce PCs, consider what kind of campaign it's going to be. Here are some relevant factors to keep in mind that should influence your choice as a GM:
If the campaign is some sort of relatively short 'gauntlet' with PvP elements, you don't need to think hard, and just throw all the PCs into the situation without a way out of it until they solve it.
If the campaign is co-op and mission-based, then of course the PCs were introduced by the employer, usually. This ensures that they are duty-bound or otherwise incentivised to stick together.
If the campaign is more free-wheeling, with the party being a rag-tag bunch of misfits that for some reason are supposed to stick together, consider asking the players to come up with a backstory that explains why they're all friends or at least allies.
If it's a fantasy game where the PCs are slightly at odds but must not stoop down to killing each other, consider making them bound together by some prophecy, or by some supernaturally binding oath that they have all sworn one way or another.