Best way to get XP in fallout 3?

I decided to play fallout 3 again on console and go for the achievements. I have all the achievements and DLC achievements except for the 3 "reach level 30 with Insert karma here karma" but after the main quests, most of the side quests, and the dlc quests I am at a low level 27. What would be the best way to reach level 30?