Practice, practice, practice. Also, FD ladders are much more sturdy than ladders that you buy at Home Depot, so most will bounce less. If it is any consolation, a ladder that "bounces" is more stable than one that does not, everything else considered. You want the ladder to give a little so it doesn't give a lot.
Also, I did the 50' at a 90 degree angle, but we called it the church raise. I really had a ladder phobia, but this wasn't too bad at all.
The more time you get on ladders, the better you will get.