Admissibility of evidence
Must be legally obtained, (obeying the 4th Amendment and other federal and state laws)
Must be competent, relevant, and material
Competent = reliable (not tainted) and credible (believable)
Relevant = tends to prove a fact of the case
Material = substantiates (supports) a point of view that is in question in the case
The Frye standard (also known as the Frye test)
Types of evidence
Physical
Direct
Circumstantial
Demonstrative
Documentary
Documenting evidence with tags and logs
Maintaining the chain of custody
Processes for collecting computer evidence
For more info, see pages 5-36 in the US. Department of Justice's Electronic Crime Scene Investigation: A Guide for First Responders.
Also, check out the Computer Forensics: Seizing a Computer white paper by your instructor.
Case Study: Brandon Mayfield