The advice for fans from the United States, England, Germany and Argentina comes as Brazil races to be ready for the tournament against a backdrop of social unrest over the cost of the event, poor public services and crime.
Much of the worst violence is concentrated in slum districts known as favelas, where so-called police pacification units have been battling drug traffickers and crime gangs.
But tourist havens in Rio -- which will host seven matches, including the July 13 final -- also suffer regular assaults and robberies while authorities recently revealed a surge in murder rates.
Homicides in Rio state as a whole rose 23.6 percent in March compared with last year, and 10 percent in Rio city itself, the Rio Institute for Public Security said in figures released Saturday.
Friday saw a fatal shooting in the Rocinha slum easily visible from the luxury hotel where the England team will stay.
Robberies were up by around a third with tourist hotspot such as well-heeled Ipanema some of the worst afflicted.
Last month, a youth grabbed a woman's gold necklace just as she was being interviewed -- about crime -- on live television.
State secretary for security affairs, Jose Mariano Beltrame, indicated Friday that 2,000 extra military police would be deployed in Rio during the World Cup.
"We are bringing forward a blueprint which will be put in place during the World Cup," said Beltrame, hoping their visible presence would "reduce the (statistical) indices."
Rio will have to manage an influx of around half a million World Cup fans -- domestic and foreign combined -- according to city hall estimates in a metropolis which last year suffered 30,489 street robberies and 12,381 vehicle thefts.
Rio daily O Dia lamented the apparent need to issue such advice as 'avoid carrying large amounts of money around,' 'go out in groups,' 'don't accept drinks from strangers' or 'don't open your door until you are absolutely sure who is on the other side.'
Noting the consulates' identification of myriad potential risks and threats, O Dia said: "In the case of Rio, the city appears as some kind of jungle where, at any moment, tourists will be subject to assault, kidnappers and rapists."
Noting a US warning that police assistance could be "limited", especially at night, the paper headlined an article Manual da Selva (jungle manual), dubbing the advice "gringo survival manuals."
And it quoted two British visitors in their early 20s as insisting that "people get assaulted every day in England as well."
The fan contingents from the United States, England, Argentina and Germany are expected to be among the largest with some 600,000 foreign fans expected in all.
The four countries agreed visits to slum areas or favelas were not advisable with even recently "pacified" ones still hosting unrest.
Germany's consulate warned fans with a penchant for nightlife to "keep an eye on your drink in bars. And don't go with a prostitute to a hotel of her choosing."
Fans of longtime World Cup foes England and Argentina are advised to look out for rather smaller creatures of the night.
"Use mosquito repellent; it can also help protect against mosquitoes that carry the dengue fever virus," England fans are urged, in advice echoed by Argentina's consulate for their fans.