When you get home, help the environment - recycle as much as you can, your paper and glass that gets picked up in front of your house, but also your cell phones and electronic appliances. Don't buy "art" pieces or other items that come from endangered species. Don't keep wild animals as pets, there's no reason to have a tiger in your home.
When you go on vacation, don't eat bushmeat from endangered species. Though this source of food is important to local people, tourist consumption drives up the price and hunt for these wild animals.
Be nice to the animals!