Since the Tophling tag is so small, I thought I'd create some more content myself
Yaling is not into PDA too much, so Toph will do little things like brushing her hands over Yaling's when they pass by each other. Slightly leaning on Yaling whenever she gets the opportunity to. And of course, her signature shoulder punch.
Yaling surprisingly doesn't mind the shoulder punches, and sometimes returns the favor. It eventually becomes a competition between them to see who can land the best shoulder punch. Sokka has had to intervene more than once.
Yaling, at first, struggles to find the right way to show affection to Toph. When she was under her mother, she was always showing affection through act of services. Her mother never really told Yaling she loved her, so Yaling didn't say it either. They just showed how much they cared. When Yaling tries to replicate that with Toph however, it leaves her with a bad taste in her mouth.
Toph picks up on how uncomfortable it's making Yaling and talks with her about it. Through the conversation, Toph reveals that she mainly shows affection physically for a reason. Toph’s parents had always told Toph they loved her, but they never completed the most basic act of love: acceptance. Because of this, for Toph, it always felt better to physically show affection rather than say it out loud.
After this conversation, Yaling sets out to find the form of affection that feels right for her. Eventually, she lands on quality time. She'll invite Toph out for walks on the beach, go to concerts, or simply surprise Toph with lunch at the metal bending academy. Toph appreciates how Yaling makes time for her, even with their busy schedules.
Toph and Yaling travel the world together. At first, it's Toph taking Yaling to some of the places she's already visited. The Gaang did travel the world, but they could never stay in one place for too long. Toph wanted to get the full experience of staying in some of those places for more than a few days.
After that, Yaling takes Toph to the places she's always wanted to see for herself. The Foggy Swamp, Omashu, even the Southern Water Tribe. Along the way, they discover locations that's new to the both of them (and to us Avatar fans.)
They always get a souvenir from each place they visit. When they do eventually move in together, their house is littered with souvenirs from their travels.
Yaling isn't really sure how to interact with Team Avatar when her and Toph start dating. After all, these people used to be her enemies. (Toph is different because Toph fully understood her situation and forgives easier than most)
It takes a while for some people in Gaang to warm up to her, and even longer for Yaling to warm up to them. No one was really holding a grudge against each other, per say. The tension mainly came from Yaling struggling to trust people again and having to shake off her non-bender bias. This caused the Gaang's early attempts to extend a hand to Yaling not going so well.
Eventually though, the tension eased up and Yaling started to become friends with the Gaang. The person who she surprisingly became closest to was Suki. Closely followed by Zuko, which wasn't as surprising.
Last but not least: Yaling tried her best to become a metal bender, but could never do it. However, she did eventually discover that she could lava bend when she protected Toph from an incoming attack.
Toph thanked her for saving her life, but still insisted that metal bending was cooler. They end up bickering about it from time to time, but all in good fun.
Hope you enjoyed these headcanons!