On foot
Walking around Nairobi is fairly easy since the city is small and places are easy to get to. However, there are some areas within the city where tourists should not go; minimise walking around at night. Thugs are rampant in many areas.
By Bus(Matatu)
Matatus public minibuses/ commuter buses are generally used for traveling between downtown Nairobi and the suburbs. Matatus vary in size, between the van sized 14 seat Matatus and the larger 50 seat buses. While generally safe, you should be aware that matatus are involved in a high number of accidents every year. Matatus are often overcrowded with more people than seatbelts and therefore can be dangerous if involved in accidents. Because there are no licensing requirements, matatusy are often poorly driven, with drivers passing on curbs, speeding, or passing in oncoming lanes while cars are oncoming. On each bus is a conductor who will hang out of the matatu and call out a price usually between 10ksh and 40ksh and location the matatu is driving. Recently the government has decided to ban the 14-seat matatus inside Nairobi, effective January 2011 in hopes of reducing traffic and accidents in town. The best choice is probably the City Hoppa bus service and of late the revived Kenya Bus Service. Beware of traffic jams on the large motorways, not only in the rush hours.
By road
Car hire from the airport is possible, and fairly painless with prices in line with other African countries. In the recent past, Nairobi had a severe car-jacking problem, but because of increased police check-points, it has become marginally safer. Traveling during the day reduces your chances of getting car-jacked, as most car-jackings occur after dark.