I just took anatomy over the summer, but didn't have to balance it too much with anything else. Of the 9 credits we had to take, anatomy accounted for 7. I was fortunate to do well enough on all 3 exams, but plenty of people in my class didn't. It's a huge learning curve and sometimes you have to entirely change how you study between the 1st and 2nd exam. Just rereading your notes obviously doesn't work as well as it did during undergrad! I think what makes it so hard is that, other than it being condensed into about 7 weeks for me, you had to know it backwards, forwards, upside, sideways, any way a question could be asked.
For most of us, step 1 was making flash cards. I'd start with muscle cards, so innervation, attachments, actions. Then I'd make cards on other things I thought I would need to pound into my head repetitively, like things with borders and contents. I take the subway to school and it's about an hour each way, and I found that my commute time was my best flashcard time. Sometimes I'd start with just 3 cards, and once I got them totally down I'd add in a 4th. Other times I would just go over the innervations of whatever we lectured on that day, depending on what I felt like doing. We did a full cadaver dissection and were in the lab every day, so as we would be cleaning out soft tissue and doing kind of menial tasks, we would constantly be reviewing attachments and innervations and actions while we could literally see and feel the muscles. Since it was summer and being stuck inside all day was no fun, sometimes we'd even just sit on the quad and try to act out actions just to make it a little more fun and memorable. I hated it, but make common lists of muscles that share an attachment or action or innervation, specific and/or general. There will always be muscles that trip you up that just won't stick as specifically as your professor wants you to learn it - for me, forget about it with the lower leg and some of the anterior neck muscles.
Drawing things out is really important, whether it's borders and contents (femoral triangle, pop fossa, cubital fossa, etc.), venous drainage, all the anastomoses throughout your body, nerve coursings. Draw to have in your notes and look at, draw it on a white board, have someone draw it out and then have them make you label it. For bone marking and attachments, definitely stare at Netter, make blank copies of Netter that you have to label, redraw things, have a friend point to landmarks, throw a bone model up in the air with your eyes closed so that you have to orient yourself when it lands. I found the Essential Anatomy app very helpful for me when it came to understand nerve coursings and blood flow since you can see everything in 3D with/without muscles in the way. I liked reading the description of where those things were supposed to go while looking at the app.
Hopefully the next exam is a little easier since you've seen how your professor asks questions. We started with LE, then did trunk, and finished with UE. By the time we hit that 3rd unit, I felt like I knew how to study, knew how to dissect, could anticipate some questions that would be asked, and was confident that I would know almost everything for exam day. Now that we're out of anatomy and into semester 2 I'm trying to figure out all over again how the heck to study for my classes. They tell us that nothing can be compared to anatomy, and that everything falls into place a bit easier after that, and I hope they're right. Sorry this has turned into a novel! Good luck!