First I'll give you a hint about ways that are NOT efficient. The best way to learn new info is not reading it in a textbook, it's not hearing it in a lecture, it's not copying it over and over a million times in pretty-colored pens, and it's not even seeing it on a patient and then reading about it later in a textbook (sorry, Student Affairs).
The absolute best way to learn new information in medical school is to be scared and/or humiliated into learning it.
"But how do I go about being scared into information?" you ask. "Do I have my roommate jump out at me and scream 'boo!' while I'm reading, as if I have the hiccups?" No. That is stupid.
Here is a handy step by step guide to being scared into learning:
1. Don't know the information to start off with.
2. Get asked simple question by attending while in patient's room ("What are the plantar flexors of the ankle?").
3. Have your mind go completely blank and say, "Umm" stupidly a few times.
4. Get prodded by the attending ("Ok, just give me one of them").
5. Make sure mind remains completely blank. Forget all muscles of the entire body. Turn your face red, say, "Umm" again to make it look like you are thinking about muscles (but we all know you're really only thinking about how stupid you feel or just repeating 'think think think think' to yourself).
6. Begin humiliation ("You don't know a siiiiingle plantar flexor? You did take anatomy didn't you?" Cue everyone else in the room such as residents, patient, patient's family, and researchers getting extreeeemely awkward and avoiding eye contact with you at all costs).
7. Be told the answer exasperatedly ("You really don't know? ((sigh)) It's the gastrocnemius, soleus, and tibialis posterior.")
8. For the rest of the day, wish that you are dead and feel woefully inadequate no matter how much else you may know.
9. NEVER EVER FORGET THE PLANTAR FLEXORS.
10. Be asked the next day jokingly by the attending what the plantar flexors are, have a brief panic attack, but then rattle them off like it's nothing. Boo-yah.
And that, my friends, is the best way to learn information in medical school.