Besides the things stated for med school prereques, your school will have a recommended course sequence. I HIGHLY SUGGEST asking an advisor about "off semester classes" and a list of all classes relevant to your major or potential minor that are only offered at certain times.
Try to stick with the suggested sequence. No one told me about the "off semester" at my school so I didn't take gen chem until my second semester. Your school may or may not do this, but at some school certain classes are offered fall or spring. So gen chem 1 is offered in fall and gen chem 2 is offered in spring. Depending on the school, gen chem 1 will either not be offered in the spring OR there will be one class for it, which makes it more difficult to get things to match your schedule if you take them in the off semester. Waiting an extra semester to take it (to have more choices for class time) then you will be behind for prereques.
Have you gone to orientation yet? Try to find out who your advisor is. Get a list of suggested course sequences for your major, preferably one that lists all prerequisites, and find out if there are certain courses only offered once a year or every two years. At most schools these will be electives but sometimes they can be major requirements. If you need to or want to take one of these you need to plan ahead to have all the prerequisites out of the way before the class is offered.
Also! Talk to your advisor about math and your ACT score. If you scored above a certain point many schools will let you skip certain classes or waive some math prerequisites. Whether or not that's a good idea depends on how comfortable you are with math. If you feel like you're really good at math and pick it up quickly, find out if this applies to you so you can free up some time by not taking unnecessary classes. If you feel like you struggle in math and they try to put you in a higher level class or let you skip something it is 100% ok to say no. This really depends on your comfort level with math I just wanted to let you know this is an option, but that its also ok not to use this option. If you do have the option to skip a math class make sure that any classes that have that as a prerequisite will accept the ACT score instead of the class.
It would be a good idea to find out who your advisor is and make an appointment with them to discuss things in detail and try to get them to help you go ahead and make a tentative plan for what classes you will take for the rest of under grad, as they will know more about the specifics of scheduling courses at your school than we will.
Good luck!
