How to study for midterms? I'm a freshman.?

Just start studying for them all as soon as possible. Study enough each day on each subject and particularly spend the most time on the things you don't know; don't spend too much time studying what you already know. Ask your teachers questions on anything you have: even if they don't give you study guides, just go to your teacher's office and ask away with any questions you have. The worst they can say is " I can't help you with that". Most importantly, pace yourself when studying and remember to get enough sleep (to avoid seizures) and avoid cramming and procrastination. Remember to eat balanced meals as well.