Taxis are only really necessary in Kigali, though taxis are available in most other major towns.
Most towns are compact enough to walk around, but otherwise a moto-taxi is a good bet. They’re generally fast but safe, and there’s nearly always a helmet for the passenger.
Rwanda has efficient and reliable public transport. Privately run buses cover the entire country and, with scheduled departure times, you won’t find yourself waiting for hours while the driver scouts for more passengers. Tickets are bought in advance from a ticket office, which is usually the point of departure.
You will also find plenty of well-maintained, modern minibuses serving all the main routes. Head to the bus stand in any town between dawn and about 3pm and it is quite easy to find one heading to Kigali and nearby towns. Destinations are displayed in the front window and the fares are fixed. Neither buses nor minibuses are supposed to charge extra for baggage.