Hey question; I've been toying with the doing color as black and white thing first method.

I'm having issues when it comes to the color. I've tried a few ways but I was curious how you did yours? ( with my finances suddenly being strapped as they are, I can't afford to get that tutorial). Is it a separate layer with just lower opacity, or is it set to something? :oa I've tried both and it always looks ugly and muddy...Hence my curiosity