If you have an idea what you're doing and/or already have a lab environment I recommend you check out the article Network access to Domain Admin for a general approach to hacking Active Directory domains.
Obvious disclaimer is obvious
The tools demonstrated in this book should not be used in an environment without complete authorization from it's legal owner. I.e. don't be stupid and don't run commands you don't know what does.
Stealth - improve article
Introduction to Active Directory
Kerberos and authentication in AD
Introduction to PowerShell
Exploiting MSSQL Servers
Client Side Attacks
Domain Enumeration and Information Gathering
Local Privilege Escalation
Exchange enumeration and attacks
Sharepoint enumeration and attack
Mitigations against common attacks
General recommendations for securing AD
Kerberos Attacks and Defense (Golden, Silver tickets and more)