As per my understanding the following points can help us (SAP Freshers) understand the SAP FI module in depth:
1. Read the SAP FI Syllabus, all 4 books religiously.
2. Practice the Exercises after every Lesson and evaluate your understanding of the topic.
3. Practice the Practical Exercises in SAP System and understand what is happening and why it is happening.
4. I try to understand a particular topic (theoretically) then practice the same in system.
5. If we can revise the whole syllabus 3 times with 100% effort, I think we will easily pass the Certification exam and answer the interview questions too.
Lastly, We should always try to find our own way to study and find out the best practices for each of us, but one thing is common for all of us being a fresher, follow SCN, attend the Open Courses and Read the whole curriculum religiously.
Thanks
Soumalya