"Ride lots."
Because you'll get to know what works for you in different situations - long, steady climbs, or short spiky steep ones. Or long, steady climbs with some short spiky bits. Reading about it is good, but knowing it is better.
I spent seven months living in a hilly area and I got to know what my body can handle - when steep grades make me blow up, what it feels to be going right at the tip of too-hard, and when even while going really hard I start to recover and can bump it up a notch, if only for a few moments. It was a good start to learning how to climb.
Too bad I'm moving to a flat state in the fall.