Try doing quests, or go to FOG (I actually did that), if you maxed the kick it will be easier. But Temple of Golem works better, you can actually breath there. Edit: ^
At level 30-35? Try out Wild Boars, Brown Teddies or Fire Boars. Double Shot will be your main DPS skill and despite its terrible attack range, is the best thing you've got.
I love the danger of being almost 1HKO'd, i don't like standing just pressing one button. Also, Wild boars is disgusting, or at least in the bottom, were there is a bunch of pigs running into each other, half of the time i was hitting with the gun that shooting, just giving aggro. i see the teddies more bearable with maxed Invisible shot. m8