When choosing colors that look good together consider using those found next to
each other on the color wheel, or analogous colors.
These are often seen together in nature and tend to be pleasing to the eye.
In the strap below, I used a burgundy red for the background and a progression of light to dark colors for the pattern. These started with light yellow in the center,
then golden yellow, orange and red.
This is one of my very rare asymmetrical designs. It also starts with light yellow in the center and moves through golden yellow, orange, hot pink and burgundy red. Then I framed it all up with very unequal border stripes of black on both sides.
Black is a color that I often use for borders as it just seems to give the
right effect for framing many designs.
Here I've chosen red-violet, blue-violet and purple for the pattern. There is one single stripe of rayon along both edges just inside the black border. The rayon, while very similar in color to the lighter violet used in the center, reflects light in a totally different way
than the other cotton yarns, providing a neat shimmery effect.
In the strap below, dark blue provides the background for a light to dark progression of blue and violet stripes. I found this one very soothing and satisfying.
This website is very concise with it's descriptions of the color wheel, color terms, and description of basic color schemes. http://www.tigercolor.com/color-lab/color-theory/color-theory-intro
I find it very helpful to have something like this to refer to.