Vehicles drive on the left side of the road in Zambia — at least most of the time.
Car rental agencies exist in Zambia, but the costs are potentially great. Not only are rental rates high $100/day, but some of the main roads in Zambia are in very poor condition. Potholes often take up the entire road, and during the rainy season, large sections of the roads wash away. As you move away from city centers possibly only a kilometer or so away you will encounter dirt roads. Although they might look solid, the dirt is often loose, and the chances of an accident are huge if you do not keep to a reasonable speed. Although you are not likely to get lost driving in Zambia there are only a few roads, you are likely to underestimate the destructive power of these roads and damage a rental vehicle, or worse, yourself! 4WD vehicles are recommended at any time and necessary on dirt roads in the rainy season, although some roads will become completely impassable then.
Remember: there are no Roadside Assistance Packages, and very few ambulances, tow-trucks, or emergency vehicles of any kind in Zambia. Given the circumstances, bush mechanics can do an amazingly good job of patching up your vehicle, but patching up humans isn't so easy!
Hitchhiking in Zambia is popular, although it can be extremely hit-or-miss as traffic density is low. Also note that, if picked up by a local, you will be expected to pay for the ride. Nevertheless, hitchhiking does not carry with it the same stigma in Zambia as it does in the States; you are unlikely to be harmed, and you might make a great connection.
In Zambia, travelers do not "thumb" a ride. The proper method for flagging transportation is:
Pile your luggage near the road.
Sit in the shade.
When you see/hear a vehicle, jump up.
Rush to your luggage.
From your shoulder, wave your entire arm up and down, palm open and facing the ground, as though you are fanning someone in front of you.
Hope the vehicle stops.
Minibuses — meaning vans outfitted with seats — are popular, but they are often irregular, dangerous, and uncomfortable. To maximize profits, a "conductor" will squeeze as many paying customers — and their luggage, or katundu ka-TOON-doo — into the bus as possible; whether or not the customers are comfortable is irrelevant. In terms of meeting locals, however, this method is among the best, and it can provide a traveler with a truly "authentic" experience. Payment is made during the journey — banknotes are passed down the bus to the conductor at the front, and change comes back via the same route.
Larger, more sophisticated "luxury coaches" exist, too. These tend to be more reliable and safer; they depart on-time; they have dedicated space for guests and luggage; and tickets may be purchased in advance. Luxury coaches are much more comfortable and are virtually guaranteed to arrive, but they might seem "generic" to a seasoned traveler.