Ride lots of hills. The best way to get better at them is to ride them. Do it in different ways too. Sometimes do the same hill in a lower gear/higher cadence seated and other times with higher gearing/lower cadence and standing. On rollers, I like to train with as high gear as I can push seated while keeping my cadence in the 80-90 rpm range. Get used to having your heart hammering in your chest and your stomach trying to find it's way outside your body. Although learning to pace yourself on a climb is a very important skill too. If you attack them too hard at the beginning, you'll blow up and will have nothing left by the time you crest it. Finally.....enjoy it. Hills can be challenging and a lot of fun with the right mind set. If you ride with friends, it can be fun to challenge each other to race up the hills. Some clubs even have weekly hill climb races in the spring and summer. Good luck.