you have to have some understanding of the existing lighting of the scene, in term of white balance, quality and quantity, can you use the power of flash to be main, or to supplement or to over power it.
in short, you need E & E, experiment and experiences.
no maggi mee here.
one more thing photographers always forget,
clients only want sharp sharp clear clear photos that show what, when, where, who, why and how of the event
if your shots can not give this two things to them, especially what, when, where, who, why and how, you are consider failed.
so keep it simple and give them what they want.