GOC requires amalgamation of various concepts in order to solve a ‘good level’ question.
Same goes with reaction mechanism which requires a high level of understanding.
Both these chapters form the base of Organic chemistry which is to follow.
I was lucky Organic chemistry was started being taught at the near end of my class 11th. As soon as it started I had made it a habit of solving questions the day a new topic of GOC was taught. For eg. if mesomeric effect was taught in the class, I solved atleast 30–50 question related to it on the same day itself(from coaching modules, M S Chauhan etc).
And when whole GOC as well as reaction mechanism was completed, I went for another round of question solving close to 100 questions which had multiple concepts application in it for enhanced preparation.
Just after class 11th exams were over, I utilised the time gap which I got between class 11th and 12th to solved many questions of GOC, hydrocarbons apart from revising class 11th syllabus.
That was my way of approaching GOC and reaction mechanism.