My first job was as a box boy in a grocery store, where we were to cart people's groceries to their car of they wanted. I loved to snap the paper bags to open them and was quite adept at cramming in the groceries. I was soon fired, for amongst other things, running into the legs of old ladies who were too slow or stopped as they were going through the doors. Hey you don't stop on the track. Why would you stop in the freaking door. Okay that wasn't really my attitude, but I was just in too much of a hurry.
My next job was driving a taxi, where I learned all the short cuts and how to time the lights etc. We had to open the doors for people, and I'd race around, try to get them in and out of the cab as quickly as possible and would be very abrupt in speaking to them. Perhaps this, plus driving way too fast down the surface streets ended up getting me fired in 6 months or so, even though otherwise an excellent driver.
Then I worked in the office for a furniture company in Los Angeles. I was doing okay but it was a high stress place, a half dozen people crammed in a very small office. One of the VP's of the company was talking with me in his office (about two steps from my desk) and mentioned something about me being Jewish. I blurted out, "I'm not Jewish, I'm German!" not stopping to think that, hello, the entire hierarchy of the company was Jewish. And heck I'm probably not even German, or if any, not much. I was transferred to the shipping department, where I sat right next to the shipping manager, who when people weren't working fast enough or doing the right things liked to say "I'm going to kill you, George" or whatever their name was. He said it to me once, and the next time the opportunity came up I said, "I'm going to kill, you, Ralph!" His head foreman was standing in the doorway as Ralph turned and said, "what did you say?" I repeated it, looking directly at him like it made perfect sense. The foreman shook his head and leave. Then the owner's secretary called and asked me for some type of paperwork. I snapped at her and said it wasn't available, then found it and went to her desk but she wasn't there. Coming back, I noticed she was in the owner's office with the other VP's. I bobbed in, gave her the information, went back to my office and was gone by the end of the week.
I made a few other mistakes since then, but not as bad as those. Generally you tend to learn things over time.
I ended up having a couple great positions, one as a supervisor in a school system, and the last one as owner of my own real estate company, now retired. People generally liked me to work with them, as I was so knowledgeable. helpful to them, and easy to get along with.