The rules of engagement: Testing the security of your enterprise – Very good basic checklist/description related to security assessments – the section on Attack Methodologies is good standard info. Short, but sweet.
You can download it from the following link: https://packetstormsecurity.com/files/download/13849/rules.of.engagement.txt
Source: https://packetstormsecurity.com/files/13849/rules.of.engagement.txt.html