how do you pick your borders

Occasionally I will find a fabric that I pick specifically for a border and work the other fabrics around it, but most of the time, I don't pick the border until the center is done. Then I audition different fabrics to see which look I like best. It really makes a difference in the overall effect when you change colors. If you stick to a similar "style" to the rest, you can usually get away with a different fabric than what is in the block. By style I mean something like batiks, soft florals, civil war prints, 1930's, etc. It doesn't have to match perfectly, just coordinate and blend in well.