My biggest tip is to not sweat the small stuff - a daily challenge. I'm hot on manners and still expect it when friends are visiting too like laying the table and thanking me for their meal etc and bringing their cups/ plates down from their room / study. Happy for them to eat upstairs as they lay on the floor and watch YT whilst eating sandwiches etc and they love that autonomy.
One tip I've started doing since year 6 SATS is to cook their favourite meals / snacks when they have exams on so every year in the summer for two weeks we eat DD fave meals. She's not keen on quiche or shepherds pie for example so cooking those would cause an "Uh not that again" and communication would shut down. It's important she feels less stressed me on the other hand can't wait for exams to be over so I can calm down
I also put little jokes or fortune cookie slips in her lunchbox so she knows I'm thinking of her. On her birthday I put Birthday confetti in her lunchbox and a party napkin. Christmas / Easter the same. If it's one of her friends birthdays she's allowed to choose a packet of chocolate bars (kitkats, clubs etc) to take to school and share with the group - they love this and think she's cool so of course I get kudos from DD.
I pick up DD and a friend every afternoon from school (friends parents do morning run) and always bring cool snacks like iced buns or Oreo cookies as always starving. On Fridays it's always a chocolate bar like a curlywurly or dairy milk. In the summer on hot days I bring ice pops in a cool bag. I always find them chatty and receptive after they've had their snack and love those 15 minute drives.
On Fridays at home DD have hot chocolates with squirts cream and extras like choc chips/ marshmallows/ mini meringues etc and call it hot chocolate with "gubbins" and we catch up briefly on the week and she shows me YT funnies and introduces me to new concepts.
We took her to watch her fave YTuber in a live show and she was so excited and chuffed and we actually loved it too and enjoyed the chat on the 4 hour journey there and 4 hours back. What was cool was it was on a school night so we brought pillows and blankets so she could nap in the back.
If DH is away overnight she will share my bed and watch girly movies that DHs not so keen on.
DD and I have a special knock that we do when she's in bed and I'm in the bathroom next door cleaning my teeth. It shows I'm thinking of her and it's a kind of extra goodnight thing we do.
I also whisper in her ear when she's at that dozy just about to drop off to sleep time of slumber that I love her and that she is amazing. She nods and smiles but I know she then goes to bed happy and loved.
Even though she's taller than me I still love to hug her like a child and and if she's upset with a bitchy friend I can pull her on my lap still and hold her close and let her talk. Not done that for aaages although hug daily.
So much more but I've already written an essay plus DH has special things he has for just him and DD too. Love these teen years so far but it's early days as not at GCSE year yet and she's yet to start her P so know that will bring different emotions - eeek!! Every day at a time is my mantra. And every day a fresh new day.