Hax of Life
Buying a car or a house is the biggest money most people ever hand over, against someone who negotiates for a living. I've been that someone for twenty years. I'm writing down how it actually works.
Cars
The number on the windscreen isn't the number. Neither is the one they come back with after "speaking to my manager". There's a structure underneath it, and once you can see it, the whole conversation changes.
What to say, when to say it, and the moment in the month when the answer is different.
Houses
They work for the seller, and they are very good at their job. That's not a reason to distrust them, it's a reason to understand what they're optimising for before you open your mouth.
How offers actually get considered, what a deadline really means, and where the room is.
This is being put together properly rather than rushed out. Leave your email and I'll send it when the first part is ready.