I buy as much dynamite as I can from Chet and then climb up the hillside by the cazador road. You can perch yourself safely above the cazadors in the abandoned campsite and blow them to bits/shoot them without fear. Then I grab my free fireaxe/chance's knife and run towards Red Rock and through the fiends collecting heads on my way. It's relatively safe and great for exp farming with the big horners, geckos, and fiends (and Bonnie Springs if you're feeling spicy).