Best quests to raise this faction (the fastest) are the quests given by the npc inside the main hall of House of Thule zone. He has 4 or 5 that you can do simply by mass killing and looting. You can PRE-LOOT the needed items and do 4 or 5 quests together. The down side is there is a 5-6 hour timer between the quests. Make sure you start out killing snakes in the area outside the building first getting the snakes/dogs quest from the froglok. When you have about 20 snake skins saved up move inside.
The outside quest is +5 faction but the ones inside are +10