What is the most common practice? how do you do it?

Do you mix the gel color in the fondant then put the fondant on the cake or do you just cover the cakes in white then airbrush the color you want? trying to decide what i should do.

I had to make a cake this weekend and had the perfect color, tried to put the fondant on the cake and it just wouldn't work, kept ripping and no matter what i added to it it didn't want to cooperate so i grabbed some more fondant and began all over again with the color then covering the cake. All that time wasted getting the perfect color on the first batch of fondant so that it wouldn't work was depressing!

just wanted to see what most people did!
thanks,
K