Evaluate all web-based information
Relevance: Is it relevant to your topic? Is it current? Is it too detailed or not detailed enough? What are the key concepts?
Authority: Are the authors experts in their fields? Has your lecturer recommeded the book or article? Who is responsible for the page? Is there copyright information or can you contact the person or organisation who created the page? When was the page last updated?
Purpose: What is the purpose of the website? Is it trying to sell? Does it represent a particular point of view? (opinions can be useful but may need to be balanced with other opinions)