This was my third attempt, I was aiming for Espeon or Umbreon (and got Sylveon twice before succeeding).
To summarize this time I:
- hatched the egg/reset the game at 7:30pm
- tried to get "average" care, only looked at it 3 times per day (8am, 1pm, before 8pm), and left the light on the last night (the night before it evolved)
- gave a loooooot of snacks (I'm sure I gave more than 300 snacks in total, both in the morning and in the afternoon, with more snacks in the afternoon)
- played no games at all