Listen to what Mr. Murphy has to say. Your instructors are there for a reason, it looks bad on them if you fail. Go to them if you have any kind of question. If they don't know the answer, they will do the work for you to find the answer and make sure that you can apply it.
Take the time to draw and understand every system they throw at you. It's not hard to remember the psid's, temp's, and levels that make automatic functions happen. Look at it long enough and it's second nature. Just make sure you can draw the system. I can't stress it enough. If you can draw it, you will remember everything else. I know it sucks to sit and draw systems over and over, but it will go a long way to get you past being an apprentice. I honestly wish I spent more time drawing systems. I made it through training shooting from the hip. I'm not ex-NAVY nor a college graduate, just a guy that put blue in the toilets and did a lot of decon work. OPS is quite possibly the best job on the planet, consider yourself lucky and grab it by the balls. If your plant is anything like mine, there is nothing keeping you from moving up the corporate ladder except for hard work and knowledge. Don't be afraid to ask questions. It is YOU that is the eyes, ears, and nose of the plant. It's up to you to make the best of it, and to be a good operator.