to take the bull by the horns
Begin to act vigorously, right away and from the most important part.
{informal}* /Начиная новый курс преподаватель сразу взял быка за за рога. — The lecturer has taken the bull by the horns from the very start of the new course./
Necessity to do something.
* /Вам наконец-то нужно собраться и начать учиться, взяв быка за рога. — You should concentrate and study, taking the bull by the horns./