Catch an Eevee
Set Eevee as your buddy and walk 10 km
Earn 2 Eevee candy while Eevee is your buddy
Evolve Eevee during the daytime while it is still your buddy
Make sure the Eevee buddy icon shows Espeon before evolving
Use the name trick once by renaming Eevee to Sakura before evolving, if you have never used it before
If the name trick has already been used, rely on the buddy method
Avoid evolving at night, or you may get Umbreon instead