Know some lingo! Learning a few words of the local language is a great way to break barriers and greet people who you come across.
Hello : Namaskaram
Thank you : Nanni
Good bye : Poyttu varatte or Kanam
Religious customs and local traditions vary enormously around the world and play a large part in the local way of life. It is important to familiarise yourself with the local people's dress codes and thought patterns. The local concept of time is also likely to be less hurried than yours. Remember that by showing respect you will be respected and appreciated yourself!
If it is necessary to wash in rivers, do not use detergents or other chemicals. There are a number of eco-friendly soaps available for travelers. Remember, it may be someone's drinking water further downstream.
Buying local souvenirs helps the local economy; whilst it is often customary and even fun to haggle, stop once you have got a reasonable price: the low price you achieve may only be due to the desperation and poverty of others.
Transport fuels the local economy and provides a livelihood for many. Sadly it also pollutes. Auto rickshaws (tuk-tuks) offer a low environmental impact of local transport.
Don't give out sweets, pens or money, especially to children. Giving to children will only teach them that begging is rewarding and can undermine parental authority. It is far better to interact with children. Simply exchanging drawings or photos can be more fulfilling and fun for both you and the children.. If you already carry something, you can leave it with your hosts and then can be distributed directly to schools or voluntary organizations.
To state the obvious, the world is full of it and you don't want to add to it yourself! Beyond that, however, it's up to you to decide how strongly you should feel about other people's litter: many walkers, for example, are happy to pick up litter along the trail. It's your call. Remember, however - many countries do not have adequate litter collection, never mind recycling or waste reduction schemes; so the less you create, the better.
You might consider taking a water bottle for your own water .
Why not consider contributing to the many projects and organisations you may have come across on your tour.