Get a Sube card, download one of the bus/subte apps that tells you which number to take, and take collectivos. (buses) very cheap, very safe, every 15 minutes pretty much 24/7. I have taken buses home from clubs at 4 in the morning, which are full of single women, ranging from 15 to 65, its nothing like a big city in the USA. Me, I take taxis when I need to, and, in hundreds, probably thousands, of rides since 2007, have never had a taxi driver try to cheat me. But in the words of Bob Dylan, I cant help it if I'm lucky...