Choose a girth size 3-4 inches smaller than you wear on pants. If you're a 34", order a 30". That way, you could add the extender straps in the back for accuracy.
The color, order it ALL MAROON, I prefer to order it by phone, based on the comments from batninja and others about sending the wrong colors or pattern. Just my 2 cents.
Boba Phat has a link somewhere about where he ordered his, price and options...already maroon as well. He did it by phone.
Robert