After the scenes, you’ll be controlling adult Aloy. At this point, you should be at least LV3 and you’ll have 3 skill points to use. I suggest getting Concentration (slows down time while aiming), Silent Strike (press R1 to takedown smaller machines or enemies from behind or while in cover), and Gatherer (additional resources when gathering).
Follow the marker to find Rost. He’ll tell you to gather the necessary materials to craft fire arrows and also talk to Karst, the rogue merchant that deals with outcasts, to get a Tripcaster. During this conversation, you’ll also get an errand to check out Odd Grata, an elderly outcast that Rost regularly helps.
While you can certainly complete the tasks Rost instructed you to do, I suggest taking this time to get used to the game by freely roaming in the Embrace. The machines in this location are weak but will put up a considerable amount of threat at your current level so getting used to the combat system, earning some extra shards (currency in the game) through hunting machines, and experience should be a good start. If you want to check the range of activities you can do at this point, refer to this page.
For the Fire Arrows, you need to Ridge-wood x2, Shard x5, Blaze x3 for a set of 10 arrows Ridge-wood is a common material that you can harvest almost anywhere but you’ll usually find a lot of them along streams or rivers. Blaze can be harvested from Striders, while shards can be collected from any machines, resource boxes, supply crates, selling items, etc.
For the Tripcaster, you have to find the only merchant icon on the map. At this point, since you’re still an outcast, only one merchant named Karst is available for you interact. Talk to him and ask about the tripcaster. He’ll ask for a Scrapper Lens in exchange for the Tripcaster. Scrappers normally appear if you leave machine remains without looting them. They have a den in the southwestern end of the Embrace in case you want to hunt for them. If you have the costume DLCs downloaded before starting the game, you can redeem them as early as now as well.
After getting the tripcaster and fire arrows, head to the camp to meet up with Rost. Use the campfire to register it as a fast-travel point then talk to Rost. During the conversation, you can ask him more questions and if you’re done helping Odd Grata, you can report it to him at this point as well. When you’re done talking to him, use the campfire to rest until evening. A cutscene will follow and you’ll be outside the Embrace for the first time.
Follow the trail and head to the objective marker. Loot the machine remains along the way, as well as other resources you can pick up. You’ll encounter a watcher along the way so take out it however you see fit. There’s a metal flower that you can pick up along the way as well. When you reach the large destroyed cabin, check out the small hill behind it to find the metal flower.
Continue following the path until a cutscene triggers. After the scene, you’ll have the task to kill the sawtooth. Loot the supply crate in front of you then crouch as you move towards the target. Use your focus to scan the sawtooth and add to your notebook’s machine catalogue. It will be better to highlight the sawtooth’s path so you’ll know where to place your tripcaster’s shock wires. Once you’re ready, equip your fire arrow and aim for the canister on its belly to deal huge damage. The shock wire should be powerful enough to immobilize the sawtooth for a few seconds, giving you more than enough time to aim for the weak spots.
Before it recovers from stun, make sure to hide again to maintain your advantage. You can place more shock wires and lure the sawtooth to them. If you managed to ignite its canister, then it should be below half its HP. Continue pelting it with fire arrows to deal bonus burning damage until you kill it. After defeating the sawtooth, a cutscene will follow and the quest will be complete.