It's never easy, particularly in a universe with such diversity in skin tones and body type to tell what clothes might look good on you.  What we've compiled here are some basic guidelines for getting a look that will suit you.  It's not foolproof, and requires some judgment, but it's far better than just guessing.

About color:

Color is not as simple as some people would like to make it.  Color is generally made up of three different attributes:  Hue, Value, and Intensity. 

Hue is what most people think of when they think of color.  It's the difference between red and blue, green and yellow, etc.  The Hue is probably the first question you'll want to answer when picking a color.

Value is how light or dark the chosen color is.  For instance, red itself can range from a dark maroon to a light pink while still being technically "red." 

Intensity is probably the hardest of the concepts to understand.  It's probably easiest to think of all colors as starting with a generic grey and adding more color through the entire range until the color is pure at its highest intensity.  Lower Intensities will make a color look more grey or washed out at times.

For instance:

 
 
 
 
This is probably the Red most people are after, but it's also one of the hardest to make and the least likely for someone to be able to do.  It's Red Hue, Medium Value, and High Intensity. This is actually the same Hue of Red that we had before, only we've reduced the Value on it a great deal to get a darker Red. This is the same Hue and Value of Red as found in the first box, but the Intensity has been greatly lowered, resulting in a more washed out look.  Once again, the same Red with the Value raised to nearly white, giving us a nice pink.

So what color goes with purple skin?

Matching the variety of skin tones in our universe is at times a challenge, and it's far too tempting to simply reduce everything to black or white and not be bothered with having to match things, but that's a very limited way to dress, and at best looks unimaginative.

But how does one begin to choose colors?  First we need to understand how colors relate to each other.

The Color Wheel

The color wheel is made up of six areas, each of which represents a different primary or secondary color.  The primary colors, red, blue and yellow, are so called because they are the parts from which all other colors are made.  They also have the distinction of not being able to be made up from other colors.  Go ahead, get out your box of crayons and try to mix up a good red using other colors, we'll wait....

Ok, now that we've established that, let's talk about secondary colors.  The secondary colors are the ones that are made by mixing the primary colors that they border on.  For instance, mixing blue and red produces purple, and mixing red and yellow gives us orange. 

Analogous and Complimentary Colors

Now that we know what a color wheel is, how can it help us pick colors to wear?  There are two more types of relationships that we need to know about before we start putting together an outfit.  The first of these is the relationship between Analogous colors.  Perhaps the best way to remember this is through a simple story about three neighbors, Ann, Al, and Gus.  Since these three live next to each other, it's inevitable that they become good friends.  Since they're good friends, they look good together in a group.  But it's just not the same if one of them isn't there for some reason, so they almost always are seen together.  Also, Al seems to be the leader of the group, and so any time you see them together you're probably going to see more of Al than the other two.  In the same way, any three consecutive colors on the wheel will work pretty well together, provided that all three are present in some way.  So if you're a Twi'lek with purple skin and want to have a two tone outfit made, consider using a red and a blue together.  It also usually a good idea to ensure that the majority of the outfit is the middle color of the three.  So for an outfit that covers most of your body, a blue with green trim might work very well.

Complimentary colors follow that age old cantina wisdom that opposites attract.  Colors that are directly opposite from each other are called complimentary colors.  They generally also look very good together, and are well suited for two tone outfits for those with skin colors that don't occur on the wheel, like white, black or browns, or even for single tone outfits for more adventurous skin Values.  So our purple skinned Twi'lek could do very well in a yellow single color outfit.

Shades of meaning...

So what happens if my skin isn't actually a strong, intense middle Value of purple, but more of a less intense light purple?  Simply adjust the other colors in a similar way and go with a pale blue and pink outfit, or perhaps a pale yellow dress.  Sometimes doing precisely the opposite, that is, going with a darker color on lighter skin, can work well, but results will vary.

But...what about my black duster?

So you still want to wear black, eh?  /sigh.  Ok, you can do that with most any skin color, but realize that pure black or pure white outfits generally tend to look pretty boring.  Adding just a little variation can really vitalize an outfit.  (Greys don't count as variation in this sense, I'm afraid...)  Experiment with adding a dash of red, green, or maybe a blue.  I think you'll be pleased with the results.

Hope this is helpful, but remember that it's intended only as a beginning for people with no clue how to work out colors.  There are many, many other combinations that can work, and the best way to find them is to try them and see.  Trust your instincts.  If an outfit looks just a little "off" to you, chances are that it is, even if you can't put a finger on why. 

Safe Travels!