The first step is to know basic weather information. Being knowledgeable in weather science is a must for all storm chasers. In fact, specialized training courses all across the world are offered to individuals and teams of persons willing to spend some quality time learning weather lessons. There is no real degree required to start storm chasing as a hobby, but it is a dangerous sport without training. (In fact, as many would argue, it is not a sport at all. It is a serious scientific inquiry into the nature of severe storms.)
As a beginner's guide to weather, you can make a start at becoming a future storm chaser by answering some of the basic questions on the Ask a Weather Expert pages. Once you get through the basic lessons, you can join the weather message boards to get even more details on becoming a certified storm chaser! I have all the details you will need on how to become a real-life storm chaser.