The European Archaeological Council (EAC) has commissioned geophysics guidelines which are available online as the second in their series of Guidelines.
Armin Schmidt, Paul Linford, Neil Linford, Andrew David, Chris Gaffney, Apostolos Sarris and Jörg Fassbinder (2015). Guidelines for the use of Geophysics in Archaeology: Questions to Ask and Points to Consider.
Namur: Europae Archaeologia Consilium (EAC).
The EAC mastercopy can be found at http://www.europae-archaeologiae-consilium.org/eac-guidlines [Note: this link calls various scripts from wix.com]
Country specific comments and additions to these guidelines will be available from this web page.
ISAP Members can purchase a hardcopy at a greatly reduced price.
Please send feedback to Armin Schmidt at A.Schmidt 'at' Bradford.ac.uk