Originally Posted by hi565
Pace yourself, pace yourself, pace yourself!!!!
That is complete key. Don't try to chase the group, do what you can do. When I did my first climbing experience I was hurting all over. But I was thankful to have a triple, before I knew it I was going about 6 mph (talk about max heart rate!) and I was cranking along at the easiest gear I could. But I did it and I just paced my way through the whole thing. And relax. Don't put a death grip on your bar, also try to keep on the upper parts of your bar to try to keep your self up right and relaxed. Oh BTW
HAVE FUN!

+1 This is really the best advice. If you're working hard early on, then drop a gear if you can. Just try to get up at a reasonable cadence. Don't try to compensate by spinning like mad. The real goal is to not be fried at the top so you can ride a reasonable pace for the rest of the day.
I think 12% is difficult, and I'm reasonably fit. I hit a .2 mile hill at 12% last week and when up in 39/23. I was standing up the whole way and definitely feeling some pain. I was wishing I had my triple by the top, too.
As a little perspective, the Mt Washington Hill Climb averages 12%. Riders who can average 6mph up that hill (over 7 miles) are considered pretty strong. No amount of momentum is going to get you up a 0.6 mile hill at 12%, so if you can hold onto 4 or 5 mph, I'd say that's pretty good. (It'll be over in 8-9 minutes.)