Rituals can help. I usually recommend that people find some place in their house to create an altar. Place on that altar a photo and some special objects of the person who has died. Spend some time there each day. Talk to the person, tell them how you’re feeling, maybe spend some time in meditation or in prayer. Use this moment to extend your wish to the person who has passed that they may be free of suffering, that they may be touched by compassion.