create Authorizations and Rols-Objects

Hi Experts,

I start working now with a new company which has a lot of problems with roles and authorizations.

Like example when we have a new MM-Consultant we are coping the same roles from the former one him without understanding what it is hiding under this rols.

Now I am trying to start exploring this area in MM SD or even programming by ABAP...

Could please recommend some docs or Blogs in this subject and advice me where I have to start--

Best Regards
Jenie