Make sure the company uses knowledgeable, local guides. The guide should be a local or at least a long-term resident, know the local language, have travel experience, and know life-saving techniques. I’ve been on tours where the guide was a walking encyclopedia, and on some where the guide was a glorified time keeper. Guides can make or break your trip. They are going to explain everything to you and keep the flow of the tour going. I always ask about the guides when I book a tour.