Mythic Destinies
Mythic characters are assumed to have great tasks and challenges they will inevitably face, culminating in their mythic destiny. While characters won't gain a mythic destiny until they choose a destiny feat at 12th level, it can be helpful for both the players and GM to start considering what the characters' destinies might be earlier in the campaign.
Some campaigns might be best served by the PCs all having the same mythic destiny; if the story is about the PCs defeating and then becoming the new Apocalypse Riders by challenging the existing Riders of death, famine, pestilence, and war, then it likely makes sense for all the players to have the apocalypse rider mythic destiny. Similarly, if the core theme of the adventure is that the PCs are all going to ascend to godhood via their adventures, the most cohesive choice for the campaign could be for all of the players to have the godling mythic destiny.
You can also use mythic destinies as high-level archetypes in nonmythic campaigns; when doing so, the 12th-level feat should gain the dedication trait and subsequent feats gain the archetype trait. You should remove or ignore abilities that require Mythic Points when using mythic destinies in this manner.