POC solo for easy XP, and Teeth. Just take your time and kill, kill, kill until you either finish or go down for the count. And I just go Pistols Only if I'm solo and using a Relic. I do max out pistols first so I have the Akimbo killing power, then work on other stuff. And I wouldn't be in a rush for XP, that will come easy enough over time. Just enjoy the game.