I worked in Nigeria for nearly 7 years and can honestly hold up my hand and say that the Nigerians treated me just fine, thank you.
My fellow workers on the other hand..........
Seriously though, don't flash your money around, don't get into any "investments", stay out of the "dark side", don't go wandering around at night........ you know, all the things you would do anywhere else.
Nigeria is no different from any other African country in as much as keeping your wits and being sensible.
Gulder & Star the local beers and they can bite!!