It seems simple and obvious. However, I seem to have this discussion with seemingly everyone, so I’m going to assume this is actually some secret sauce that I have uncovered: the quickest and easiest way to up your skill level is to double check your work.
I think math class burned the phrase “check your work” into our minds with some negative connotations. I also think people are just generally trying to move too fast, and attention to detail really suffers in an era of incessant multitasking. Doing something 80% or 90% of the way may be good enough, but good is the enemy of great. If you want to be a high performer and to have a sterling reputation then you need to set the quality bar high and keep it there. If you hand off work that is actually incomplete or wrong then you gum up the works, you look unprofessional, and you waste valuable time and money. Don’t make people double check your work for you unless that is what they are literally paid to do (i.e. editors, auditors, etc). Even then, your goal is to make their lives as easy as possible so they can work efficiently instead of cleaning up stuff you could have caught yourself.
One of the great things about this piece of wisdom is that it is universally applicable. Ordering, writing, cleaning, coding, building, planning, presenting, calculations. It doesn’t matter what you are doing, it will always be to your benefit to double check the quality before handing something off.
Should you re-read that email you wrote to make sure you don’t sound like an idiot? Yes, you should. Should you review your own pull request, or better yet, review your code before making a pull request? Yes, you should. Should you double check that everything in your Amazon order is correct before buying? Yes, you should.
Start building the habit, and eventually it will become second nature. It is amazing how many things you will catch and how many snafus you will avoid by simply taking a few extra minutes to look things over. And, if something is really important, then go over it three or four time for good measure. Call it quits there though. There are diminishing returns, and it will either be good enough or it needs peer review from someone else with fresh eyes.