At your children's age I think the best thing you can do to prepare for a healthy relationship in regard to behavior issues (which I think is what a lot of people mean when they say discipline) is to find yourself some good resources for evaluating age appropriate expectations and typical child development. A large percentage of discipline "mistakes" I feel like stem from the parent not having these skills. I like the Louise Bates Aims series and also rely pretty heavily on a typical college child development text.
From there, one of my favorite "beginner" discipline books is "Becoming the Parent You Want to Be". This book is very flexible and non-judgmental and will help guide you to finding a style that works for you and your family.
Other good basics: Try to phrase things in the positive (tell the child what you want them to do rather than what not to do), be descriptive in your praise, identify the times when it's best to be consistent AND when it's best to be flexible, take care of yourself!, discipline in "the now" rather than for some distant future behavior, don't talk too much (lest you end up sounding like the teacher in Charlie Brown).