I have seen your question. What I feel is you can very well start your career in SAP as per your mail you said that you had experience in retail. With my experience I suggest you to start learning SD module (sales and distribution) or MM (Material Management module) only one module is enough to understand the business process in SAP.
After taking training on either or the above courses, learn SAP IS retail module. which would help you a lot in getting jobs in sap field.
This is my sincere suggestion and advise to you.