Study and focus tips

So, I'm looking for studying tips.

How do you usually study?

My whole elementary school and high school I didn't learn how to study.

I would just listen in class, at home read and repeat.

But I'm in med school now and this doesn't work.

I'm loosing my focus, sometimes I just get lost when I read I don't pay attention when reading.

I think I just never learned how to learn since I used to pay attention in class and that was always enough.

I have concentracion problems in everyday life also, sometimes when when someone tells me to do smthg I just forget, if I don't do it right away or if I don't writte it down.

And now when I need to learn tons stuff by myself I just don't know how+"getting lost" problem

How do you usually study?

I want to do smthg about it but I don't know how.