Hello Karthi,
You have got right inputs from Sebastian. It is an advantage you've got a Maintenance background. Besides all these one ultimate truth I believed based on experience is that I understood things only when some realtime mapping was done for different processes of the company. And this was gradual process. It does not and can not happen if we put efforts and read all this material. When we start mapping the realtime processes your background helps and this prompts you for improvisations. Last but not the least, your primary support/teacher has to be SCN. You'll get almost everything already discussed and with solutions. (Google search with string starting with SAP word and your issue). I have seen people attending class room trainings but could not grasp things until they worked on the system with realtime issues.
This is out of my personal experience.
Good luck
KJogeswaraRao