1. Generosity - It doesn't matter what you give her, she will always want more. Never give without getting, no matter how large or small. Save your generous spirit for closing the settlement deal at the very end.
  2. Marriage Mindset - Like it or not, the beginning of your divorce is the end of your marriage. If you go through your divorce acting like you're married, you're going to get steamrolled. Don't ask, act. Those little nice things you used to do - don't, unless you have an ulterior motive related to achieving something in the divorce. You can hope for reconciliation until the cows come home but 99% of the time, reconciliation is a ruse that will just set you back further and exhaust you emotionally.
  3. Anger - Anger is natural, anger is real. Anger needs to be dealt with and vented. But if you ever show her anger (unless contrived and strategic for a purpose), you lose. Showing any pain or emotion during the divorce to her is a loss. And guess what, she doesn't feel sorry or care.
  4. Conflict Avoidance - This goes hand in hand with the marital mindset. Pick your battles but before you pick your battles, stake your ground. Creating some conflict early on and pushing back will have the effect of reducing conflict later on. It is counter-intuitive as we desire keeping the peace and harbor hopes of early settlement, but by pushing back early and often you reduce the bullying and the impact of her creating conflicts later on.
  5. Reactionary Responsiveness - Slow your communications down. Narrow to a single channel. Turn off notifications. No text battles, no matter what she says. You don't need to respond to anything that is not the business of the divorce. If you do need respond, be measured and do so after a cooling off period. True emergencies are few and far between.
  6. Financial Surrender - It's easy to think we can buy ourselves out of the pain and get things done. While financials are a great lever, by giving away the farm early, you lose your leverage. Additionally, we often toss our financial future out the window. Do not do this. Financial negotiations in divorce are positional - this means that if you start with a fair offer, you will end at less than a fair result. If you start with a generous offer, you will get an even less fair result. Counterpoint: Making a "first best offer" which is more than she is strictly legally entitled to and clearly indicating it only goes down from there can work in some circumstances.
  7. Appeasement - Giving in to aggressors only makes them more aggressive. Rewarding shitty behaviors by engaging only encourages more and shittier behaviors. Giving up ground in the house, time with the kids, money, anything like that - without an exchange or too early on only indicates weakness and it's hard to recover from it. EDIT: Hand in hand with this is guilt. No matter your role in the divorce, you don't deserve to be abused or throw away your future.
  8. Overly Reasonable - We have a saying in litigation - the first side to act reasonably loses. Was your stbx a bastion of reasonableness during the marriage? Will divorce magically change that? Probably not. Will your stbx learn from your example of reasonableness to become reasonable during the divorce? Absolutely not. Don't reason your way to ruin. Nickel and dime. Push back. Ask for more than is "reasonable".

BONUS: Be kind to yourself - this is a rough time and everyone makes mistakes, truth be told very few mistakes are game changers so just do your best. Care for yourself - find a peaceful space to occupy to recharge. Start your recovery early by standing up for yourself in the divorce!

EDIT: Thank you for the award, kind stranger!

EDIT2: Woke up to two more gildings - thank you kind stranger and /u/dday_throwaway3 !!!

EDIT3: Thanks to /u/deadlycatch for another gilding, so happy people are finding value in it