Solve problems outside contest. You don't need to do every contest. I only did them when I felt like doing them. Took me about 3 and half a month to get to pupil, but I only did 10 contests in this time.

Solve harder problems, at least +200 rating problems than your current rank. Solve around 1200+ problems around 30-40, or less if you get comfortable. Don't waste too much time on 1200R problems. Start solving 1400R problems after a few 1200R problems. And 1600R problems occasionally.

You will never get fully comfortable solving problems of specific rating if you keep solving problems of that rating only. So, to get good at 1200R problems, solve 1400R and a few 1600R problems.

Personally, I felt 1400R problems are usually easier than 1200R, it's probably just my imagination

I answered because you became expert

I have become expert

just submit A question wrong in a contest :)

You need to solve problem 56 days a day, no less, and no breaks. You may consider leaving earth for your training.

few days to few months. I have seen problem tutorials only a few times of all the 700 problems I have solved. Usually, I just leave it to solve latter. And I have solved many problems in this way.

But this may not be your best choice of action. I don't see editorials, that's a personal thing.