My proposed plan for 1-50 for cleric (suggestions needed)

For lvl 8-12 you could be doing the Beginner Mage quests, decent exp, you can also move to the slime tree. I agree with Walter for the Pig Dungeon and Caution Falling Down. Once you hit at least 25+, I'd suggest hunting Sand Rats outside of Magatia, great spawn, and you could also do the Ariant quests (Sand Bandits and whatnot) for very fast exp.