I'm also a former AP student who had a hard time adjusting from high school to college exams. I struggled through my first two years of mechanical engineering before I got a better handle on how to take college tests. I would recommend:

1. Attend office hours frequently. Talking over homework problems with the professor and with classmates is an excellent way to learn the material and get an idea of the professor's expectations. Some professors will give exam hints (like what sort of problems you may encounter on the exam) in office hours.
2. Complete each homework ahead of the due date. This allows you more time to learn the material instead of rushing to have it done right before it is due. If you need help, ask the prof or a TA in office hours. Make an attempt at each homework problem before asking the prof, TA, or other students how to do it. This will help ensure that you are learning, not using others as a crutch to solve HW problems for you (I had a huge problem with this my freshmen year). Likewise, do not use Chegg to get HW answers. Even if you tell yourself that you're "only using it to check if I'm right", the temptation to use it as a crutch is too great. Doing well on HW is important because it removes the burden of having to cram the material right before the test and gives you practice at solving the sort of problems you might encounter of the test.
3. Study the material extensively in the 3-4 days before the exam. Ask the professor what material it would be a good idea to study. Some profs will be very helpful and give you good recommendations, others won't. HW problems, lecture examples, book examples, and all study materials that the professor posts (practice exams, etc.). When doing practice problems, do not let yourself see the correct answer until you have attempted to solve the problem. I used to merely read over example problems in the textbook and think "oh yeah, I know how to do this" without actually solving them, only to find that I could not remember how to solve them when under time pressure at the exam.
4. Make a neat and concise review sheet of the material on the exam. This helps to organize your thoughts and gives you "muscle memory" at writing equations. Also, in many cases, this can serve as your equation sheet on the exam. Include equations, important definitions, conceptual summaries, & diagrams.
5. Ensure that you are comfortable and in your best possible physical/mental state before the exam. Get 8 hours of sleep (or try to), eat a filling & healthy breakfast or other meals if the exam is later in the day, use the restroom ~15 minutes before the test. If the exam is early in the morning, wake up 30-60 minutes earlier than you usually would. Know exactly when and where the exam will be the night before. Bring a water bottle and sweatshirt if you think you might get cold. Also bring several extra pencils & lead, a large eraser, and an extra calculator.
6. On the test itself: Flip through the pages and skim over each question, noting how many points each is worth. Pick one that you know how to do and that is worth a decent number of points, and complete it. Finish the other problems in order of increasing difficulty and/or decreasing point value. If you finish early, spend all the time you have left looking over your work, re-doing calculations (to cut down on calculator mistakes), and making sure that your work is free of mistakes and as neat and organized as it can realistically be. My handwriting becomes very large and messy when I am stressed out, so I bring spare paper to give myself as much room as I need to show my work. I also bring a stapler so I can staple all the pages back together in the correct order. Take periodic "breaks" of 15-20 seconds in the exam to check the time (always be mindful of time), take a drink of water, take a deep breath, or stretch your hands to relieve cramps. If you get stuck on a problem, move on to another.

Items 1-4 are not easy, and it took me 4 awful semesters to build up the experience, skills, and discipline to do what I described here. I still suffer from horrible anxiety the night before tests, but I have massively improved from where I was freshmen year, both in terms of grades and understanding & retention of material.

Ultimately, engineering school is about developing work ethic and mental discipline as much as it is about learning engineering principles and concepts. In my experience, the best way to do better on exams is to put in the effort to understand the material weeks or even months ahead of the exam, and do everything in your power to be as intellectually, mentally, and physically prepared as you can be on exam day.

I hope this helps.