Hi Arun,
The initial boost to learn any new concept in any field is our own curiosity and passion to learn/excel without thinking about the potential benefits or materialistic things.
As you already hold good amount of SAP FICO experience plus have some ABAP knowledge, I suggest you better go for S4 HANA with Simple Finance because that will actually add value addition to your profile since you have FICO + ABAP knowledge and you seems also interested in ABAP ( which many finance consultant find hard to do).
1) To begin with, you can start learning the concepts, logic's, requirements and benefits of simple finance.
2) Then, you should first try acquiring as much as knowledge from various sources such as google,scn, other SAP forums, SAP Simple finance experts( if you know someone )
3) As rightly suggested by Siva Prasad Vasireddy, you can contact some good & genuine institutes in your city that offers SAP simple finance training with sound exposure to real time scenarios. Read, Learn & Practice every possible concepts starting with simple one then graduate it to complex one.
Probably, I believe that by following above steps and of course with your own heart & mind course plan you will surely get into very new ,challenging & demanding career where you can grow in coming years.
All the Best.
Thanks and Regards,
Shakir Shaikh
SAP FI Consultant