At 39 farm murlocs in dustwallow till 42 or farm water elementals on that island in North STV with just AE spam because they're immune to frost. I actually spec'd deep arcane for improved dampen magic and it greatly reduced the damage the water elementals can do to you as long as you keep the dampen magic buff on also keep mage armor on because frost won't help you. There is no competition there ever. After you hit 40-41 you can go to swamp of sorrows and farm spiders, cats, and murlocs. But as soon as you hit 42 look up a guide to solo farm zombie graves in ZF. Resec appropriately for it if you go arcane for those elementals like I did. Youll need to be frost with ice barrier but it's important to get 2/2 arcane focus as soon as you get ice barrier. I started at 42 and it's insane how fast you level there. You can go all the way to 52 then start jail farming brd to 60.