Hi
I completely agree with TW. 98% of expertise of SAP comes by on job experience. However, I suggest SAP Certification ideally to get an entry into SAP world. I am not discouraging you, but MS may not make any additional difference to you.
As far as modules are concerned Order to Cash (SD) and Accounting to Reporting (FI) are going to be ever green and modules which are in demand. However, wait for release of S/4 HANA Simple Finance.