Ladies, how did you determine your color palette?

I think I will always have a variety of colors in my closet and have no problem wearing colors that just make me happy. But I'd really like to splurge on a colored coat (might have to be next fall at this point) and bag that really "work" for me and don't require scarves or makeup, etc to look right. I am super clueless- I don't even know if I have a warm or cool complexion.

Did you figure this out by trial and error or through some other magical method?