How did you choose an anonymous sperm donor to conceive your child?

March 9 |
@offbeatfamilies runs these advice questions as an opportunity for our readers to share personal experiences and anecdotes. Readers are responsible for doing their own research before following any advice given here... or anywhere else on the web, for that matter.
Photo by Grace Hebert, used under Creative Commons license.
My partner and I are just getting started with trying to get pregnant using donor sperm. Though we are a straight couple, we need some outside assistance. However, trying to think about all the options is a little overwhelming.

We live in the UK, so the system here is a little more regulated than in the US, and we're pretty sure that we want an option where the child/children can contact their donor when they're 18, if they want to. My question for those of you out there in similar situations who might have used donors or are in same-sex couples that might have also used donor gametes: is there anything we should be thinking about now that might help us later? And, if you feel comfortable sharing, how did you go about narrowing down which donor to use? — Alicia

If you used an anonymous sperm donor, what factors weighed into your decision about whom to choose?