I had my colours done when I was 13 and only vaguely remember the experience.
I am in the process of renewing my wardrobe post-baby and a couple of threads on here reminded me that I have kept the little book of colours. I assume it will be useful for choosing clothes but I can't remember if there any guidelines how to use it. All I remember is that I'm a 'winter'.
I think you can do a colour rerate or something for about £45. I don't think your season changes but your best colours might have and it would refresh your knowledge too. [[http://www.houseofcolour.co.uk/other_services.htm#wakeup_makeup here]