Linux:shell: how to change color of your prompt

I find a good paper:

http://www.funtoo.org/en/articles/linux/tips/prompt/

to teach you how to change the color of your prompt. Actually I did this change long time ago, however, there is a problem in my setting. I didn't use "\[" and "\]" to include the string so that my shell cannot precisely calculate word-wrap and once I input long strings in the command line, my line will mass up.