First. Read EVERYTHING you can about the subject. Make damn sure you are ready to do this. Life at 30 is different than life at 24. There are some that say it is reversible, but it isn't totally a guarantee. Plus, once you have someone cut into your scrot, it isn't something you want to repeat (TRUST ME).
Many downplay the impact of pain, but it hurts immediately. Sometimes in a small percentage of men (Oh lucky me) it can hurt for a long, long time afterward. Wander on over to
Post Vasectomy Pain.
Knowledge is key...How about a nice condom. It covers the fertility aspect and protects you from all sorts of other nasty things. Surgery is a very final thing.