My first requirement was that she was proven. And by proven, I mean had done a previous DE cycle which resulted in a live birth(s). Just having a child, doesn't show how she'll probably respond to stims, etc.
Second, I wanted a donor up to around 28 y/o. I had sudden POF at 22 y/o so I know age isn't everything, but I wanted to try and help up the odds at least.
My donor was 22 y/o, we were her second donation. Her first resulted in a live birth and my cycle resulted in twins with six blasts on ice.