Every semester, I see students struggling to retain the details of the endocrine system, but the good news is that the endocrine system is one of the easiest systems when you approach it the right way! The first three minutes of this video gives a suggested plan of study and the remainder uses ADH as an example to show you how to retain the details about a specific hormone (i.e. target, stimulus, effect and homeostatic imbalances) with minimal memorizing!
PS - Don't forget that understanding is not the same as remembering! Just because as you watch you think it all sounds logical, doesn't mean you will remember how to put it into action later. Write down the basic plan for yourself so you have something to refer back to.
Do you understand the difference between positive and negative feedback? This is one of the FIRST concepts you are taught in a physiology course, but in my experience, many students forget what these terms mean by the time they become important!