I took the GRE but it was in the early 1990's (yikes!). It was a paper/pencil test then. It was a tough test. I am not a math person so that was my biggest struggle. I didn't take a prep course but looking back, I should have! My score was good enough to get into grad school and that was all that mattered to me.

Best wishes to you. Maybe someone here will have taken it more recent that me and have some up-to-date pointers.