How to Change Colors Within a Double Crochet Stitch
To change to a different color within a row or round, the new color is introduced on the last loop of the stitch just before the stitch that will be made in the new color. This method makes a smooth transition to the new color.
Below, I've outlined, step-by-step, how to change to a new color within a double crochet stitch.
Begin with old color:
Yarn over hook.
Insert hook in the next stitch to be worked.
Yarn over hook.
Pull yarn through stitch.
Yarn over hook.
Pull yarn through 2 loops on hook.
Drop old color at this point. Continue with new color:
With new color: Yarn over hook.
Pull new color yarn through last 2 loops on hook
(one double crochet made, with a color change). The next stitch worked will be done in the new color.
Photo How-Tos For Details Of Changing Colors Within A Row (What To Do With Unused Color Strands, And So Forth): http://crochet.about.com/library/weekly/aa041203.htm
More How-to's here: http://crochet.about.com/library/weekly/aa052398.htm
This article and photo copyright 
2003 by Sandi Marshall, licensed to About.com, Inc. Free
for your own personal use only.