It was both mine and her first time doing it, and after 3 and a half hours, I made her orgasm, but she was shaking quite strongly for about a minute before (and during) the orgasm. Like I said, it was my first time, so did I do something wrong?
No, this simply means that her body was reacting with full body, high frequency, low intensity muscular convulsions in response to the sexual stimulation. It is not exactly common, and doesn't happen with every orgasm, but it is perfectly natural.
