Either win by Serra Angel's commander damage, by stopping your opponent from blocking Serra with enchantment auras, or just keep pecking away at your opponent small creatures with flying.
There are also a few precious life gain cards that can help this deck go the distance; Suture Priest, Lone Missionary, Soul's Attendant, Soul Warden, Goldenglow Moth, Trained Caracal, Whitesun's Passage, Chaplain's Blessing, Sunspring Expedition, Recumbent Bliss, Ajani's Mantra, Caravan Hurda, and Divine Offering. It may not seem like much but added together, I estimate that there lifegain cards can be a game changer.
There are only 36 lands in this deck because it isn't mana hungry. Usually, I prefer 40 mana, but I don't think that this deck needs it.