Both Livingstone and Victoria Falls have tourist information offices where you can expect pleasant, friendly staff working with limited resources. Livingstone's is situated at the tourist centre next to the main museum, where Mosi-oa-tunya road bends into the centre of town. it's open Monday to Friday, 08.00–17.00 (closed 13.00–14.00) and Saturday 08.00–12.00. You can pick up brochures and get referrals, but agents and tour operators are usually better geared to assisting you with actual bookings. The Victoria Falls office is a small bungalow opposite the wimpy on park way. for details of local tour operators.
Important note on visas
In recent years both Zambia and Zimbabwe have changed their rules on visas, requiring more payments for crossing the borders. Zimbabwe's visas proved the major problem, seeming excessive to the operators in the Falls area, who relied for their livelihood on a free flow of people across the border. (Visitors may stay on one side, but would want to take part in activities on both sides.)
Fortunately, for those visiting Zambia, a deal has been reached whereby you can enter Zambia to do an activity or even to stay, without buying a visa – provided that the operator you are going to gives at least 24 hours' notice to the immigration authorities. They basically just need to put your name on a list down at the border post, and you pass through free.
So remember to book your Zambian accommodation or activity in advance by a few days, and you generally won't need to pay. However, to enter Zimbabwe is another story entirely.