All sound and proper advice. I would add that you must make sure your relationship is rock solid and that you are aware of what you both want out of the lifestyle. vtjames742 is correct in that, many times, it starts as a purely male fantasy.
Men do not always think things through with the correct part of their anatomy and many relationships fail on the rocky shores of cuckoldry as many ladies become attached or "bulls" decide to push too far.
Above all else, the two of you must STAY IN CONTROL, even if you are pretending not to be. Personally I love the humiliation but I have boundaries and safety "nets" to make sure we stay within what we have agreed. Equally the wife (who like most women, are far more intelligent than men) knows exactly how far she wants to go and has safe "phrases" where we can go from being sub to VERY DOM in seconds. This lifestyle is for you and your partner in a loving relationship. You allow other men into your relationship, but they should always play to your rules, even if they think they are in control.
Many "bulls" think cuckolds are automatically sissy, or enjoy dressing up or being used anally. That is not actually the case in many respects and, unless the husband genuinly wants that, it wont happen.
Find yourself a respectful and ideally experienced "bull" to start with who will play to your rules and treat everyone with the respect they want. Once you are comfortable you can then start to "train" your own "bull"