First impressions are much, much, much more important than anyone can imagine. You've been told they are important, but you may not realize how true that was. People like to make a decision about a person and it's incredibly difficult to change it once that happens, especially when that impression/decision was also shares among others. If you start a new job and do really well at the onset and everyone thinks highly of you, it's insanely hard to get rid of that even if you were to completely botch something. You could come up with some reason and everyone is likely to assume that reason is true and needs to be addressed rather than the problem having been you. Similarly, digging yourself out of a hole from a bad impression is perhaps even harder.

The value of hard work is also understated. Most people do what they need to do and that's it. They also don't really internalize the challenges the company faces. If you take that one, you are far more likely to succeed in your job. It's not just about "hard work" but an entire mind set that most people simply don't have. If you have it, it seriously pays off.

Related to the previous point - working a bit longer also really pays off. This is different but related to the previous point. There is definitely a non-linear increase in earnings once your surpass the standard work hours. Spend an extra 5-10 hours a week on your job or side project/business pays off much more.

You can either work "smart" or work hard. Technically, you can do both but hardly anyone does. The few that do, however, are absolute rock stars.

No one checks anything. Everyone just assumes everyone else is doing their job and doing it properly. Even if checking things is part of someone else's job, it's usually done half-assed. Actually verifying the important stuff (and sometimes the less-important stuff) opens up a world of potential where your business discovers all kinds of missed opportunities, incorrect work, etc.

Most people are bad at math. And most people are also financially illiterate. Which by extension makes a huge majority of people really, really terrible at personal finance and financial planning (for themselves or their business). This also applies to a lot of smart and successful people.

Every organizational structure that human beings create yields towards tyranny/abuse over time. Doesn't matter what you are talking about - government, business, anything. Over time nearly everything somehow seems to become these oligopolistic style structures where there are a few hugely powerful entities and then everyone else.

Related to the previous point, far more things follow the pareto distribution than I could have imagined. In fact it seems to apply to anything that either has any creative aspect to it at all or to non-creative endeavors if they have any sort of scalability to them. There's a small group of people that are so insanely efficient and productive that it's almost impossible to comprehend. For example, I used to work with a guy who was working full time with me and started his own side business which was an online SaaS that he paid someone to create for him after he wrote up all the requirements and he did all the testing. While this was going on he also spent every free second trading cryptocurrencies and made a small fortune doing that. When the product was ready he launched it and manually sought out retail (end consumer) clients one by one via things like Discord chat rooms where he would pump his software that was tailored to individuals. He spoke to literally thousands and thousands of people and convinced them to sign up. Then he had a recurring monthly revenue which dwarfed his (already high) salary so he quit to pursue it. He continued to get clients and now has north of 15,000, most manually acquired. He's working on launching a sister product now. It baffles me how he can even do like half of what he does.

In business, managers are very hesitant to grant permission but much more likely to grant forgiveness for not following procedure. So in many cases it is usually better to just do whatever it is you think is best for the business and try to improves things however you can if the rules are (or will) prevent you. The personal boost here is also that your manager also thinks your plate is fully loaded with whatever it is they've already assigned to you. Then you shock them with this big thing you've also been working on and they're shocked you were able to take that on. Win/win.

There was more that I had, but I forgot it while writing the rest above. But I suppose that's enough blather from me today.