Science communication is a diverse and transdisciplinary field and is taught most effectively when the skills involved are tailored to specific educational contexts. Few academic resources exist to guide the teaching of communication with non-scientific audiences for an undergraduate science context. This mixed methods study aimed to explore what skills for the effective communication of science with non-scientific audiences should be taught within the Australian Bachelor of Science. This was done to provide a basis from which to establish a teaching resource for undergraduate curriculum development. First, an extensive critique of academic literature was completed to distil the communication "skills" or "elements" commonly cited as being central to the effective communication of science from across the fields of science, communication, education, and science communication. A list of "key elements" or "core skills" was hence produced and systematically critiqued, edited, and validated by experts in the above four fields using a version of the Delphi method. Each of the skills identified was considered by experts to be mostly, highly, or absolutely essential, and the resource as a whole was validated as "Extremely applicable", within the context of teaching undergraduate science students to communicate with non-scientific audiences. The result of this study is an evidence-based teaching resource: "12 Core skills for effective science communication", which is reflective of current theory and practice. This resource may be used in teaching or as a guide to the development of communication skills for undergraduate science students in Australia and elsewhere.