Personal security in Rio / brazil
Go to uruguiana metro, buy a vasco camisa. Wear it everywhere except high security areas, ie lobby of a 5 star hotel; put the vasco in your pack, and be ready to put it on anytime (eg, I did in an unplanned nightime trip to city fo god favela, or anywhere at night, especially in zona norte)
Put surigcal gloves in your pockets at all times;
always carry a tampon an electrical tape (sticks to itself) in your pack; learn to dress a gunshot or stab wound, including on yourself
Carry a cell phone at all times; if a criminal comes at you take his picture; be prepared to call police (190, or get officer of day of local mil pol battalion)
Be prepared to swim near water; wear goggles around your neck, and put your wallet in your surgical gloves, learn some basic swim strokes.
Make real friends.
tip everyone, especially the lowest class people (maids who watch your shit in the roparia at the luv motels) a little, always.
Stay away from gringo areas (copa, ipanema)
Fighting in a country where the 3 F's are the national culture (fighting fucking futbol) is even dumber than fighting in any foreign country as a rule