All the topics are connected to each other. For example to know about alkly halides, first a student must complete the topics alkanes,alkenes and alkynes.

I will suggest you to finish every chapter if possible. Be thorough with the most basic things of every chapter. And yes if a chapter is started then do not leave it in the middle because in examination it creates a problem if question is asked from that chapter and student only knows the answer of half of the question. Other half because was not done during the preparation, the question in the end remains unsolved which leads to losing of marks.

If you still have any queries feel free to ask in the comment section down below.

All the best.

The paper for chemistry is  very balanced as almost every topic is covered and questions are moderate in difficulty. 

Coordination compounds are a must to be done. 

Thermodynamics is important. 

Atomic structure and redox reactions. 

Chemical bonding and d and f block elements .

Read NCERT thoroughly. 

Good luck