Moving from Oracle RDBMS password authentication to Global Active Directory Authentication

I have a situation where I am maintaining a lot of the same individual user schemas on a lot of databases.  I am not an LDAP expert, nor am I an Active Directory expert.  So, I am looking for the best approach that will allow me to manage all my user authentication except for service accounts through Active Directory.  I would like to end up in a position to evolve to where not only user maintenance/authentication is handled through Active Directory, but some database authorization could be handled through AD groups as well.  I would like a solution that will