UPD: I found a good solution for my problem and I want to share it here. I relied on people’s help, but I kept trying to carry out my own research that turned out to be very useful. Perhaps, someone will consider this information useful and will need it. The first source that helped me was Stanford blog

— I got some time-managing tips and recommendations that will help me spend less tim on homework and be more productive. Admissions board recommended me to submit a recommendation letter, but my employer hasn't written such papers before. Therefore we found a guide on writing a graduate letter of recommendation from an employer and we wrote an amazing paper. It let me increase my chance of being accepted.

newspaper turned out to be a great source of general information about my future studying, so I already know what expects me. If someone still has any questions, don’t hesitate to contact me.