Catch or obtain Eevee
Raise Eevee’s friendship/high happiness
Level up Eevee during the daytime
Make sure Eevee does not know a Fairy-type move if you are using a game where that matters
Avoid leveling up near a Moss Rock, Ice Rock, or using a different evolution method
If playing a game with affection and friendship, keep Eevee’s affection/friendship high
If playing Pokémon GO, earn 25 Eevee Candy and evolve Eevee during daytime while it knows no Dark-type evolution name requirement is needed only for Espeon
If playing Pokémon GO, set Eevee as your buddy and walk 10 km, then evolve it during daytime after earning the required hearts or using the name trick once per account if available
If using the name trick in Pokémon GO, rename Eevee to Sakura before evolving it once
Confirm the evolution happens into Espeon when you level up during daytime with sufficient friendship