Sis asked, "How do I know what season I am?" and I thought that deserved its own reply post.
First, start off on the sidebar - http://hearth-tobelovely.blogspot.com/2011/05/colors-and-you.html
Next: If you don't want to buy the book (remember: the first version only, with four seasons, not 12), I'll give you the gist. (The book is nice, if for no other reason than you get a full palette of 'your colors' - and there's a good chance at finding it at a used bookstore, since it dates from the early 80s).
Having gotten some bits of fabric in radically different colors and sorted things into "that looks nice" and "oh dear, am I coming down with something?" you then put the colors that work well into a general category. Winters wear cold/clear colors - white, black, clear greys, jewel tones (ruby, emerald, sapphire). Springs wear warm/clear colors - turquoise, coral, light navy. Summers wear cool/muted colors - soft greys, navy, all the true pastels (pink, baby blue, baby yellow). Autumns wear warm/muted colors - browns, forest greens, orange.
There will be crossover! I have very vivid coloring, and I've gotten tagged as both a Summer and a Winter, while I am actually a strong Spring. How did I tell? I pulled up lavender (Summer) and black&white in a stripe (Winter) and tried them... awful. I would say that those would be great check-colors, and straight pumpkin orange (or Hershey brown) is a good check for Autumn. For Spring? Probably a greenish-super-bright-turquoise, which is just going to be a bit *much* on everyone else. Springs can wear the most outlandish colors... even more so when they're young. I used to actually look *good* in electric coral. I know, scary stuff.
When you're sniffing down the trail, a starting point can be your original skin and hair color. Are you warm or cool toned? You flip your arm over and look at your wrist - is it ivory or pinkish? Is the palm of your hand corally/peach or more of a true pink? That will help you aim for cool or warm. Usually redheads are Autumns. Sometimes you'll find a Spring who's a strawberry blonde or auburn au naturale, but the true redhead is an autumn. Black hair, like a raven's wing? Winter. "Mousy" hair? Probably a Summer. (My 8yo's brown hair has a silvery-grey cast to it).
Then you're looking at your natural self - are you high or low contrast? Winters look great in high-contrast colors! So do Springs - I love to rock blue and red or green and pink. Instant makeup. :) Autumns and Summers, not so much - but they make quiet colors amazing.
Hope that gave you a start...