Battling an winning a lot helps it to I recommend the Battle Chateau with a Black Writ.
Walking 128 steps
Getting a massage (Cyllage City)
Using EV berries
Soothe Bell (Shalour City)
Pokemon-Amie? Play fun games feed it puffs have a darn good time in less then an hour lol....not sure if it works but rumored to also raise happiness a bit.