Payal you have 4 years of preparation that's good and indeed the best you can do is just give your 100% for SSC CGL preparation. Go through the syllabus first. Tier I, Tier II, Comprehensive Writing, Subjective exam. Each syllabus should be in detail and you stick that syllabus in your study room.

For Tier I - GK, Reasoning, Maths, English.

For GK make a notebook for regular current affairs updates. Go line by line for Lucent GK. Practice one day one topic whatever you read.

For reasoning practice the sets of previous year exams of SSC CGL and RS Agarwal.

Maths is the tough nut to crack in CGL but every day a regular practice of 5 hours will make you perfect. For maths tier II question paper sets, Kiran publication tier II advanced maths, 10 years question bank of CGL and all other SSC exam.

For English practice, take previous year set questions of SSC CGL.