I didn't know roofs from what, and made a 12 - 12 pitch, which turned out
to be terrifying for nailing on the shingles.

http://home.comcast.net/~glyford/shed/shed.htm
and scroll 3/5 of the way down.
http://home.comcast.net/~glyford/shed/Shed-06.jpg
http://home.comcast.net/~glyford/shed/Shed-roof09.jpg

A contractor friend showed me how to make the staging and loaned me
the roof jacks. Without them, I'd have spent a lot of wasted motion
moving ladders back and forth. The other trick I've seen is a bar
that mounts to a ladder that then lays flat on the roof, and the bar
hooks over the ridge...

I was talked into making it 10x12 by the board of health, who didn't
want to hassle with a permit for a mere shed. If I had to do it
again, I'd say "heck with that!" and make it at least twice as big.
Second thing I'd do is not have the roof drip water in front of the
doors that don't ever face the sun. I threw cheap gutters on it this
fall, but I'm pessimistic that will help much.
--Glenn Lyford