I use to be an absolutely horrible climber. Roads that appeared to be completely flat would send my heart rate into the stratosphere, but I kept working at it. After 3 or 4 months of riding every day I attempted a hill near my house that was about a 10% grade. I only made it half way up the hill. A woman stopped her car and come over to me and asked if I was having a heart attack.
It took me another 3 or 4 months before I could climb that hill and another 2 months to climb the 14% hill on the other side.
Well, I can climb any hill near me now as long as the climb is no more than two miles. However, I am still not a fast climber. I think little old ladies can beat me up hills, but in day they wont.
Hill climbing just requires persistence and determination. I made the mistake in the beginning of trying to climb every day. I have been told that I want to keep the climbing to one or two days per week at the most. This gives your body time to recover.