Biological materials collected in harsh environments such as archaeological excavations, at crime scenes, after mass disasters, in museums, or non-invasively in the field constitute a highly valuable source of genetic information. However, poor quality and limited quantity of the DNA extracted from these samples can be extremely challenging during further analyses. Here we have reviewed how degradation, decomposition, and contamination can affect DNA analysis, and how correct sample collection and storage methods will ensure the best possible conditions for further genetic analysis. Furthermore, highly efficient protocols for collection, decontamination, and extraction of DNA from minute amounts of biological material are presented.