The most important thing to have with you when you go into the field is information. Take a moment to consider all the factors from road access to moon phase. Write down the essential information. Hopefully, it all fits on a 4 x 6 card you can slip into your bag.
For ethical reasons, we don’t want to draw attention to your witness, their family, or their property as a result of the site visit. Plan to keep a low profile and blend in. Leave non-essential gear at home and take a minimum size team.
This video goes over the basics: