I am an English Grad presenting at a NASA conference; what's the best way to prepare?
Different fields have different standards of what to expect in a presentation, from how it is organized, to how the 'powerpoint' is used (or not used). Even what constitutes notions of powerpoint agony for the audience will have some minor/major differences. (Science audience will want you to be simple, please). Presentations in an english department and a physics department will be a different in style and standard organization.

I would strongly suggest going to someone in one of the science or engineering departments in your university (perhaps someone who is charge of senior project courses who regularly has to work with training the undergraduates in how to give 15 minute presentation in the normal style of the field) and ask them for advice and copies of the usual documents they pass out to their students on how to give a scientific technical presentation. (Maybe have that faculty member in the audience for your practice talks)

And, assuming that the school year will start before you need to give your presentation, go to a few of the colloquium  (or student presentations) in that department just to get a sense of the style expected.

My experience (I am in physics/applied physics/materials) in attending seminars occasionally in the humanities either for fun or because I was serving as the university representative on a PhD defense, is that it is mostly stylistic expectations that are different. Good scholarship is good scholarship, and once I figured out my shortcomings in what different cues I needed to watch for in the humanties presentations, I could follow their work and be impressed or not.