There's alsot of answer to that, but,
1) Do not destroy their habitats
2) Do not kill them for their body parts
3) Do not feed them
4) Do not bring wild animals back home.
That's all
Many people believe hunting should stop because it is considered to be animal abuse. Humans hunting animals, who are innocent and cannot defend themselves is sometimes considered inhumane.
By not poaching
well you can stop animals from being extinct if you don't eat them and if people stop shooting them or using them for bate
reproduce them and give them space to live in
It is possible, but the technology is still being improved, and securing specimens for some species would be difficult.
To prevent killing of animals we should :- 1.>Try becoming a vegetarian and stop killing and eating animals. 2.>We should stop buying things made up of animals or any parts of it. 3.>We should stop going to circus to prevent ill treatment of animals.
actually, it's people cruelty that we should stop. animals aren't cruel, they just operate on self-defense and instinct.
helping them
they can cut down the pulution and stop littering
You can stop many beautiful animals from becoming extinct.
About the time humans go extinct, but maybe not even then.
Plants will be dead.Eventually animals also will be extinct.