Learning how to properly bathe your bird can be helpful for a variety of reasons: perhaps you are going to show your bird. Perhaps you have vent gleet, or your bird is a gross mess and just needs a bath. A bath can also reduce allergens and feather dust and makes a house bird smell nicer.
First gather your supplies: three 5 gallon buckets, pure ivory or classic dawn dish soap, vinegar, a towel, a blow dryer, an old toothbrush, petroleum jelly or coconut oil, paper towel, and some hypoallergenic unscented wipes or saline wipes for the face. After bathing is also an excellent time to trim nails and beaks if nessesary, as bathing softens the toenails and clean toes are easier to see the quick in.
Set up all three buckets next to one another, either in your bathtub or outside, and fill each bucket enough to cover your bird's back when you put him in. In the first bucket, add a little dish soap. The second bucket is plain water. The third bucket gets a glug of vinegar in the water. The vinegar makes the feathers extra soft and shiney. The water should be lukewarm, not cold or hot. Have your towel nearby before you start, feathers soak water up like a sponge.
You are now ready to bathe your bird! Gently hold your bird with both hands and clamp the wings to his sides as you lower him into the bucket. Make sure that at no point does the bird's head go underwater, as they can and will drown very easily! Always keep the head above water! As you lower him in, he should be able to comfortably stand in the bucket. The close sides of the bucket help confine movement and help keep the bird calmer. With the bird standing in the tub, keep one hand over or under the back or breast as needed to control movement and prevent drowning or flailing. With the other hand, start washing the fluff. Make sure to agitate the feathers without rubbing the barbs excessively, as this can damage the feathers. Once you have all the soil off the fluff, grab the bird and gently move him up and down in the water to agitate the body feathers without rubbing or breaking them, like a plunger. My children call this the "whoosha whoosha" phase. Once body soil is removed to your satisfaction, you can then lift the bird out of the soapy water. Let him drip a few moments, then move him into the second bucket for the first rinse. For the rinse, you simply do the plunger agitation motion again, making sure all soap touched areas recieve a good rinsing. Remove your bird from the first rinse, let him drip a moment, then proceed with the vinegar rinse. Give the bird another thurough agitation making sure the feathers get rinsed, and then lift him out. Squeegee the bird a bit by petting in the direction of the feathers before wrapping securely in the towel.
If you wish to wash the face, this is when you use the baby wipes or saline wipes. Be extra careful around the eyes! Sometimes a toothpick can be a good tool to clean the nostrils, but care must be taken not to poke your bird in the face if you do this.
Once this is done, bring on the blow dryer! Most people are suprised to find that, although most birds do not enjoy water baths much, chickens and turkeys that i have bathed all love the blow dryer, going so far as to nearly fall asleep as i lift the wings and blowdry every feather. The fluff is especially important to blow dry, as it can become a matted mess otherwise. Use the warm, not hot, setting.
Once your bird is dry, you can use the toothbrush to buff the legs and feet, and add a thin layer of petroleum jelly to the comb, wattles, and legs of your bird for a beautiful shine, using a bit of paper towel to wipe off any extra. You do not want your bird goopy or he will attract dirt on those nice clean legs! This is also the time to trim and shape his nails and beak if nesessary. Once you have finished, step back and admire your bird. Beautiful!