A good and EASY way;
Do the dog quest in real time with spiked knuckles (let them surround you, Hell, let them kill you, just DONT MOVE). Get the directions to the scavenger's camp. Collect up 6 junk, get the 200¤, get two train tickets, go up to Hell, do the ant quest in real time (same deal). Collect up even 8 junk. Go back to LA, sell off that junk, buy 2 more train tickets, repeat.
EDIT; You shouldnt do this forever, but for a few levels, until you can take on bigger game.