Outdoor ones can be complicated. More orbs will show up especially at night. There are more bugs, pollen, dust and other things that will create orbs galore. Just be cognizant of this. Also small animals sound huge when you don't know what they are or where they are.

While prepping for this investigation, I would became familiar with the local wildlife in the area.

Wear comfortable clothing and bring clothing for any unexpected weather, i.e. rain or cold rain, sleet or snow. Bring some good flashlights and extra batteries. If you can walk the place during the daytime that will help you get familiar with landmarks and the landscape. It will be safer so you don't fall off a cliff or step into a hole and get injured. Make sure you bring a backpack to carry equipment, food, water, first aid kit and cell phone plus whatever else you might need. Like bug spray.

You didn't mention how long or what time of the day the investigation is so I tried covering the main things I could think of for night investigations. Any other information provided would be welcome.

But most of all, have fun.