How to study properly? And stop procrastinating?.?

[Sean]

Ok so I'm 16 and I've been told for years that if I just applied myself studied and stopped procrastinating I could get straight As , I usually get high Cs without studying .. Now I have a reason to study (I hope to study medicine I've wanted to since I was a about the age of 6 but always taught I was too stupid so I tried to convince myself it wasn't for me..now I can't see myself doing anything else..)
So how do I study properly? And how do I stop procrasting! I spend way too much time on social media .. Also how do I study maths properly? I mean I can't really just look over it.. And chemistry too how do I study over it., so that it stays in my head (I sound extremely stupid for someone hoping to study medicine I know)
Don't say oh medicine isn't for you if you don't like studying.. I do just I'm not very experienced.. I know it's what I want, and because it's something I enjoy i won't mind studying!..thank you