Speaking from my experience I would focus on getting good with scheduling and more importantly learning what work for you when it comes to grasping the material for each class. Figuring out what works for you is in my opinion the big thing because it's so easy to get lost early on in this program. There will be a ton of resources and examples on how to schedule ILs, doing multiples passes, reviewing, etc thrown at you that it's easy to try and emulate those and not find success because it's just not right for you. Personally, I was never big on rigid schedules with every time slot carved out and I tried it at the start of the program because that's what I saw most people doing. I quickly gave up on it and settled for simpler task lists on what I had to get done for each day and that worked for me. Same goes for managing your classes, do what works for you for each class. You'll be told about anki, quizlet, bootcamp, many other resources to study. Try as many as you can for each class and see what clicks for you. Ideally, you can use the summer for experimentation because you'll get a sample of what the fall science courses entail. Don't be afraid to change strategies if something isn't working for you just because it seems to be working for someone else.
I'm not going to into class specific strategies, that's something that was covered during the summer session my year so presumably they'll do it again and can offer more in-depth advice. I will say is that the program really is just a numbers game and if a class is weighted more heavily (worth more credits) try to dedicate some more time to doing well in it. Excelling in biochem (which was worth the most credits) will help make your life a lot easier come spring. Certainly wish I did put in even a little more effort for a slightly better grade to make spring less stressful for myself but somehow I pulled it together and still made contract, so even if things don't go as well in the fall remember you still have the spring.
Not to drag this out any longer concerning approaching the rigor of the program, remember that you're not doing this alone. You'll have TAs, staff, and everyone else in your cohort. Particularly your cohort, there was a a real sense of camaraderie between everyone from what I could see since you're not competing for spots and everyone could get in if they meet the requirements. So, get to know people and the program will heavily promote forming study groups as another resource to help you succeed.
