@Babalaas- Sustainable tourism development has been taking off in the past few years, becoming a multibillion-dollar industry. This has also led to a problem with ecotourism that is rife with green washing. Tours simply play lip service to being environmentally friendly without actually doing much that is environmentally or socially beneficial.
My advice would be to plan an Eco tour of your own. Plan a trip to a place that you enjoy and immerse yourself in the culture. Be sensitive with your transportation choices, opting to be a pedestrian or travel through mass transit. Leave good tips and do not push too hard of a bargain for souvenirs. Try to spend money at places where preservation of a natural or cultural resource is the purpose of the attraction.