B.Sc

As you all know the syllabus is huge. So, start preparing few months before the exam.
Don't get messed up with the topics out of syllabus. Stick strictly to your subjects syllabus.
Meticulous study is the correct approach that can help you resolve all your doubts and attain lucid perception of various theories, concepts and their uses regarding the syllabus.
Try to solve as many as mock test papers & previous years papers, especially 1-2 months before the exam, as it will give you a clear idea about the difficulty level, pattern, & how to allot minimum time to solve particular type of questions. This will help you know yourself, your capabilities & the field in which you are lagging.
You should give at least 6 to 7 hours daily to your studies.
The best way to prepare for the exam is preparing a time table and then sticking to it throughout the preparation tenure.
Refer to standard books only, and prepare hand-written notes.
Don't take any stress, eat well & try to sleep at fixed time and for at least 7 to 8 hours a day during your preparation.