I am a master student in mathematics. For me a large part of doing mathematics is thinking about, reading and verifying the proof of theorem that I find them in my filed of study. I can do this action in 3 ways:

• When I see a theorem I get a paper and think to prove it: this action takes time a lot and maybe I couldn't prove it after thinking for a lot of time.
• Finding the proof of the theorem in a book or in the internet and begin reading ,going step by step with proof ,understanding and verifying all steps: this action may takes time a lot and maybe it is not necessary that I read all steps and it's better that that I jump from not important steps (but how I can find that a step is not important?).
• Finding the proof of the theorem and just read it like reading a newspaper for finding the sketch of the proof: this action is good because of it's speed but maybe there be some important details in the proof that we couldn't see them in this type of reading.

My questions:

• What is the Way that famous mathematicians like fields medalist take it for reading the proofs usually?
• Which way is the the best for Which proofs? (for example classifying proofs and saying that the first way is good for the first class and ... )