1). Follow standard books and check syllabus regularly to make sure that you are not going in too deep beyond the scope of Gate, follow lectures on MIT, Nptel or whatever resource you feel is good .
2). Decide time regularly to competitive coding, because no one can escape it if he/she wants to survive in Computer Science.
3). Coding regularly would make your mathematics and reasoning power better which would help you a lot in gate to understand most of the concepts in various subjects very easily.
4). Your Algorithms and Data Structures would become good during coding and you don't have to make much effort in these subjects theoretically because you have done practical work.
5). Gate exams is basics only, so make your basics strong and you'll make it.
6). Since you are in first year so most of the subjects you would encounter in your upcoming semester that are also in gate. So check you complete syllabus and check which all subjects have to be done in your upcoming semesters and prepare those within that semester only, prepare them as you are preparing for gate exam, make your concepts strong that even your teacher admires you.
7). Best book for each subject is like this :
CLRS for algorithms + Data structure , Galvin for Operating Systems , Tanenbaum for network , Korth for DBMS, Peter linz for Automata, Rosen for discrete , Ullman-sethi for Compiler, Ritchie for C . Hamacher for COA, Mano for digital .
8). You have a lot of time to plan and study so just plan what all subjects you have to complete in which semester. Since you are a B.Tech student so no one better than you can teach you how to plan ( Like we plan to study which topics to read two days before the exam)
9). Improve yourself daily, update yourself daily.