Are you colorblind? If so, this will be difficult.
Do you know any women you can ask about this? Women put a lot of thought into "their colors," because they tend to wear much bolder colors than men.
That's another important point: classic men's clothing can be done pretty well even if one ignores color. You can do a lot with a relatively limited color palette.
If you're extremely pale, you shouldn't wear really dark colors (obviously no black suits, but aim for lighter shades of gray and navy), and white shirts are most effective either at night, or on a person with some color to their face. Even DiCaprio, there, is a little washed out by his white shirt and would look better with a light blue.
Don't forget that the idea of wearing flattering colors only applies above the waist. Wear whatever you want below the waist.
That might be a bit basic. Now, in terms of more practical advice: I don't buy ties online, because I need to see them. My taste in shirts is pretty orthodox, and I'm buying basics, so I don't concern myself with unusually-colored shirts -- I'm relatively secure that I'll look fine in another light blue pinpoint. I won't buy anything extreme online.