Assuming asking for JEE Main, The important topics of Organic Chemistry - Purification and Characterisation of Organic Compounds, Some Basic Principles of Organic Chemistry, Hydrocarbons,Organic Compounds Containing Oxygen, Organic Compounds Containing Nitrogen, Bio Molecules etc. The books you can prefer For Organic Chemistry- Organic Chemistry by Paula Bruice Yurkanis, O.P. Tandon Organic Chemistry and Organic Chemistry by M.S. Chauhan.

The preparation tips you can follow given below:

Make a plan to manage Time Well- Make a time table and devide your time in two parts first your study plan & secondly your daily routine works. Within stipulated time you should finish the syllabus. You must draw certain goals. Depending on the difficulty level of the chapter or the topic, You must decide for yourself in how many days you will be able to finish it. Before proceeding towards the new topic, you must ensure that you finish the previous one and Revise thoroughly.

Go Through with the Syllabus - You must be well versed in the syllabus of JEE Main 2019. You should know the topics from which the questions will be asked. This will help you to divide your time.

Practise with the previous year Papers: Go through well with the previous year papers, It will help you to know the level of the questions.

Good Luck!