Re Angela's comments - the Goleman texts are a good theoretical introduction. In my experience, he comes in for fire on two fronts. Some of the psych community sneer at the quality of his research, and I have also found that in trying to introduce EI principles to clients, they normally struggle to 'get' what is being said in any of the Goleman books.
In the final reckoning, it's the application which counts. The question then arises; 'for what purpose do you want to become adept in EI?
' and once this is addressed, one can start looking at EI adept behaviour as the easiest path to fluency. From a practical application view, I recommend clients to start thinking 'before I carry out a particular behaviour, what will be the result of that behaviour on those around me?' This helps to develop better impact assessment, and therefore forms the steps to EI fluency.
As a practical application, I recommend 'Winning Behaviour' by Terry Bacon and David Pugh as a very readable and valuable text.