Since yours are white, you'll probably want to pick up some bluing shampoo (typically found in the dog section of most retail stores). Whites tend to stain, the bluing shampoo will help with that. Be careful though, if you use too much, you'll turn them purple! As for general bathing, lots of folks use different techniques. The most common seems to be a gentle baby or dog shampoo, then a rinse in diluted vinegar water (to cut the soap, if you choose to use the bluing shampoo, use it first) and then another rinse in clean water. Bathe them a few days to a week before you plan to show, so they can preen their feathers out again. They tend to look a little flat after being washed, and it strips the oils from their feathers.
Good luck!
