You don't. Gte the lantern from the monastery, and take a photo of the footprint in the snow. But Mews is not convinced so you don't go back. Instead, once you have proved the other three cryptids (Nessie, chupacabra, and Jersey Devil), he sends you to hunt Bigfoot, who is similar to the Yeti.
You don't find a photo, you take a photo, on the trail above the monastery in the Himalayas. You also collect the lantern there. But back at the Mews lab, the footprint is not convincing proof. You don't have to go back to the Himalayas. Get the proof for the other three cryptids (Nessie, chupacabra, and the Jersey Devil) and an opportunity to get the Yeti/Bigfoot will present itself.
Since the monks won't let you test the Yeti scalp, you have no proof. Once you have the lantern and the footprint photo, you can find nothing at the Himalayas. However, once you prove the other three cryptids (Nessie, Chupacabra, and the Jersey Devil), Mews will send you in pursuit of the similar creature, Bigfoot.
You can't, because it never appears. You do find Bigfoot at the end of the quest. All you can do at the Himalayas is get the lantern from the monastery and a photo of a footprint high up on the mountain. This is not enough proof. When you prove the other three cryptids, Mews will send you after Bigfoot instead.
There is no yeti footprint. You have to find all the other cryptids first.
You don't. However, you will later follow Bigfoot as he travels through the trees in the Pacific Northwest.
There are 3 you have to prove: Nessie (Loch Ness) Chupacabra (Puerto Rico) New Jersey Devil (New Jersey) You can't get what you need to prove the Yeti, so you are sent to find Bigfoot.
On Cryptids, you go to the Himalayas and ask for the Yeti skull. He will not give you it, but you will be handed a lantern to 'light your way' as he claims.
You don't. After you get the lantern and the footprint photo, there is no other proof available in the Himalayas. Once you prove the other three (Nessie, Chupacabra, and Jersey Devil), an opportunity will come up to chase Bigfoot instead of the Yeti, since they are similar creatures.
A person can get a yeti guide in Cryptids by visiting the Himalyans. A yeti will appear and the player will have the option to pick him for hire. The yeti will also provide the player with a lantern for future travels.
on top of the temple :)
You have to look for Bigfoot/Yeti in the Himalayas, the Jersey Devil in New Jersey, the Loch Ness Monster in the Loch Ness in Scotland and the Chupacabra in Puerto Rico.
The proof for Nessie is a photo from Loch Ness. The proof for the chupacabra is a tooth from Puerto Rico. The proof for the Jersey Devil are egg shells from its nest in New Jersey. You cannot prove the Yeti, but when you have proven the other three, you go to follow Bigfoot, which is a similar creature. (see the related questions)