Sneaker41-I think whatever field you choose to specialize in it has to be something that you are passionate about because it is your passion that will help you through the tough times.
If you are doing this simply for the money then you will not be successful because you will lack the passion necessary to get you to the next level.
You will also tire of the business sooner and probably want to drop the pursuit of that business altogether. Being an independent contractor is a lot of responsibly and it is not for everyone.
For example, during the real estate boom many people became independent mortgage consultants and now most left the industry because they really did have an interest in the field and were looking for fast money.