Boxing is a good start. I'd learn how to profficiently kick and grapple as well. Perhaps San Shou or Muay Thai would be better to start with. I'd really recommend a more traditional art though, with a fuller arsenal. Now I will spark a livid debate in this Jeet kune Do forum: Forms may not be good for fighting, but they have many other advantages. You will gain better coordination, agility, speed, and definitely better technique. Though Lee was against forms, they were still an integral part of his training, and they were partially responsible for his superior technique. That is why I recommend a traditional art before you move on to the chaos that is JKD. Discipline your moves before you let them be free.