Hi,
I have a BS in Fire Science, not engineering at all (it's for fire service folks). However, I have an MS in FPE, and passed the FE first try.
I had a very hectic schedule in the months before the FE, and took the Other Disciplines FE exam. I got a hold of videos and watched them on the way to work taking public transportation. I worked through as many problems as I could, but I'm not going to say it was a lot by any means. I'm not the smartest cookie by any means, a very hands on learner we'll say.
Also, as icing on the cake, a fire alarm went off in my apartment at 2:30am the morning before, and I had to clear the air from burned veggie pasta. Had that smell in my nose the whole time. Barely slept.
Best advice I can give you is to know know know that equation manual you are given. If you can spin those equations around, which I think I'm fairly good at, and get down the basic principles of what they are asking, you'll do fine.
Best of luck!
RT