Always live on less than you earn - don’t get into ‘life style inflation’. Sounds easy, but if you added up earnings vs spent each month/year, most people with rent or mortgage, credit cards and their overdraft would actually live about 10% over their income, and then desperately try and make it up/pay it back by using their tax return or holiday loading or overtime or dramatically cutting down for a month or two. This is stressful. Just always live your life at 90% of your salary, or less. If you want a better life, you need a better paying job first.
Agree with the poster that said in a disagreement or difficult conversation, think, where do I want to get to in this conversation, and what do I need to say to get there. Don’t yell and ‘get things off your chest’. Don’t think ‘they had that coming’. Think intelligently. Achieve the outcome. You can always yell in the car to yourself on the way home. If you do blow up, not only have you not solved the problem, but it’s still there to be solved, and now you are coming from behind.
Aways have enough money in the bank to make choices an option. Eg - leaving a partner, booking an expensive flight to see someone before they die, saying yes to last minute holiday with best friends/sisters to your dream location, stretching a bit more to get your ideal house, giving some money to someone who desperately needs it. Whether you say yes or no to the important choice, it’s not yes or no because you can’t afford it.
Like others - most people don’t care about you (not in a bad way - a liberating way). So don’t make decisions with them in mind, as they aren’t considering you.
Also, don’t tell very many people how you are feeling emotionally. It’s like bleeding next to a shark.