During a trip to Tanzania you may, as with anywhere in the world, come across crooks and dishonest people. There's no need to be paranoid, it's the same deal as with anywhere else. By being prudent nothing bad should come your way.
As a tourist, the most likely problem you'll have is thieves and pickpockets.
If you're white, they'll assume you're rich. You're their favorite prey. Just remember that petty criminals target tourist spots, public transport and markets.
Assaults are usually after dark and in big towns. They're more common in Arusha and Dar es Salaam than elsewhere in the country.
Road trips are also more dangerous after nightfall. There are crazy drivers and it's also possible to fall foul of highway robbers who'll strip car drivers clean.
A word in your ear about drugs. Apart from it being illegal and bad for your health, going out to score a joint or two will put you in the presence of people you really don't want to meet - avoid this at all costs or you may find yourself in a lot of trouble!
Con artists will find you all by themselves. You don't have to go looking for them. They'll try to over charge you and you'll be asked for donations to fake orphanages, schools or other charitable causes Some tales are VERY tall and it can be difficult to tell the truth from a lie.
First piece of advice. Don't advertise the fact that you're a tourist when on vacation in Tanzania. Don't wear flashy jewelry, nice watches nor hang your camera around your neck. In other words, be discreet, don't attract attention, walk with confidence and show people that you know where you're going (even if you don't).
Don't play the hero if you're attacked. Don't try to fight back, don't try to mimic Jackie Chan! Don't resist, just do as they say.
Whatever the reason, don't give out money in the street. There's a strong chance it's a set-up. If you want to donate to a school, for example, get in touch directly with the institution or teacher in question. Don't give handouts to kids.
Even if Tanzanians love to discuss and debate things, don't get involved, particularly if politics is on the menu.