First get all your items together. A deep sink will help. Grab Dawn dish washing detergent, a soft brush, and some towels.
Now go and catch the sweet bird you plan to wash. Carefully lower bird into soapy water and use brush to clean feathers and feet.
Once all dirt is washed away. Rinse with warm water and bundle bird in a fluffy towel. You can either use a blow dryer on low heat or let the bird dry slowly in a warm safe place.
Now you can use a stiffer bristle brush, like a toothbrush, and smooth out all the feathers. Focus on encouraging the oils from the skin out and over the feathers.
Now using an oil, like coconut oil, you can oil the legs, toenails and beak. This is not only good for those scales and hard surfaces but also makes them shine.
Return bird to a nice clean cage with soft bedding for them to relax in. A darkened spot, say with a towel over the cage, is best. Some birds are stressed out by being groomed and need time to recover.