The UW-Madison campus offers many career resources. You should first look to your home departments for examples of resumes from your majors, then think about how your environmental studies major or certificate complements it.
The L&S site also includes a great section on resumes and cover letters.
While on the site be sure to sign up for Buckynet! BuckyNet is a partnership between the College of Letters & Science, School of Human Ecology, Business School, College of Agricultural and Life Sciences, School of Education and Wisconsin Alumni Association. It is an online system meant to assist UW-Madison students in their job and internship search.
Be sure to browse the PDF of power verbs.