Energy return on energy invested (EROEI)
Come up with realistic goals and expectations for the volunteers. Know that they are either working for free or paying you to work, their time and energy is valuable and they will have an expectation of you.
Should you ask about age, gender and diet?
Age is important to know as it will offer you a rough idea of their degree of life experience, maturity level and how well they will mix with the current dynamic at your project. While age is not always a definitive indicator, it can help.
Asking gender offers you an opportunity for gender balancing and diversity. Do not make it a mandatory question or a simple male/female question, as we now live in a non-binary gender world, where people have many different identities or are still unsure on how they identify themselves. There are many social and political discussions around gender and some people have identities that are different from their biological disposition.
Diet can be a delicate subject for some people and a non-negotiable one for others. With volunteers, the host/mentor often offers some type of meal plan. You need to review your own budget and availability, as well as time and staffing resources to feed volunteers. Perhaps one of the volunteer jobs is to cook for other volunteers. This is a reasonable and standard job for a volunteer, but you have to reflect on the training that will go into using the kitchen, being mindful with resources, etc. Some applicants may have a strict diet that would cost you a lot to accommodate. It is important to create your own standards for staple foods and perks, and let it be clearly known to the volunteer that they may have to supplement their diet.
It is important to ask logistical questions about dates of participation.
Finally, be sure to ask about any health concerns and for their emergency contact information. The volunteer is your responsibility when at your place. That being said, make sure to inquire about insurance and other legal liabilities for hosting a volunteer.
Remember that everyone makes themselves sound great. Engage your intuition, give them a look on social media and check references. Sometimes if the vibe feels off, it probably will not work out.
These volunteer programs all have applications. Peruse for examples, or apply...and go!
Punta Mona Center for Regenerative Design & Botanical Studies
United States & Canada:
The Ecology Center
The City Repair Project
Eco Villagio Torri Superiore
Greening the Desert in Jordan
Happy Toes South Africa
Permaculture Institute Asia
Noosa Forest Retreat