Make sure your eco-holiday is truly eco-friendly before you book. Concerned travellers should attempt to minimise their impact on the environment. Ensure all rubbish is carried out of the area, and water and fuel are used sustainably. Ideally, book only tours which use tourism to promote conservation and community development.
Travellers should ask: how does this trip make a positive contribution to the local environment and to local people's lives? Is tourism being developed as a sustainable alternative to more environmentally harmful activities, such as logging?
You should also ask what evidence is there that the local people want tourism and what do they get out of it? If the answer is jobs, then how worthwhile are these jobs - are locals being employed as cleaners or managers?