A & P has got to be the most difficult class to get a handle on it's just hard core memorization of the body systems and how they work. I can't offer you any real memory tips and tricks but I can provide this bit of advice. When you're learning about each system, think about how the body systems respond and are affected by variations down the line. Here's an example. Hypernatremia. How does the body respond? What the receptors detect is too much salt, so, to fix it, the brain tells the digestive system to drink more water. Does this decrease the salt content? No, but it dilutes it to the point of reduced risk to the body. In truth, hypernatremia is typically caused by dehydration. The salt content in the body is usually normal, but it's the water content that is reduced, resulting in higher serum levels.
Hyper and Hypoglycemia are similar, Hyperglycemics have a loss of appetite, nausea, vomitting, frequent urination and excessive thirst. Why? The body is trying to prevent food (sugar) intake by getting the digestive tract to remove as much as possible, urinate as much as it can to remove the glucose from the body, and thirst to get fluid into the body that would dilute the glucose as well as feed the kidneys.
Hypoglycemics are the opposite, they get hungry, wanna eat, not urinate, and try to get those glucose levels back up.
A&P is likely the most important class you will take because you will learn to think about how things work in the body and more importantly, how they affect other parts of the body when they don't work properly. Once you get the hang of it, the rest of class will be a breeze because you'll be able to look at a patient's condition and with a reasonably high index of suspicion be able to identify the root cause of the problem.
On another note, if I may ask; why is your user name the symbol for commerce and banking?