hmm... well, for
me it's almost
never one trick as each performance is different, as well as each person's output.
additive and subtractive eq are the more promising methods to employ. using exciters and compressors that maintain a particular characteristic is also very helpful.
i guess if you are asking
"what is the best way to make a horrible vocal sound good?" ...the answer would go a little something like this.
-track the performance like your life depends on it
-edit!-edit!-edit! the performance with the
best comps available
-use additive and subtractive equalization
-lower the dynamic range of the vocals in an effort to increase the signal level (compress then limit)
-hope for the best response from the talent and audience
9/10 reasons why the vocal performance sucks is due to the lack of confidence in the talent... the other 1/10 reason is because the talent isn't really all that talented to begin with.
it is what it is.
hope any of this makes sense.