It is easier than you expect to bathe them,and,most accept it and do enjoy the attention.
I bathe mine in a washing up bowel,next to my kitchen sink.
All my birds are filthy with mud now,so rather than just feet and leg washing,I am giving them a full bath.
As the feet with feather's are really muddy,I would suggest having just warm water,to cover their feet first,they will sit in it for quite a while.Which helps to soften the mud.
Then use water with either baby shampoo,baby bath,washing up liquid or a diluted mild human shampoo in it,The girls love the bubbles,the boys sort of bluster a bit now-and do try to get out :lol: .
Wash all the soap and mud out,you could have to do quite a few rinses.Just ensure you rinse until water is clean with no soap left.
It is surprising how little shampoo/bubble bath you need per bird.
I do sort of wring my birds out

,I stand them on my draining board on a tea towel/kitchen paper/thick hand towel and gently squeeze the water out,which they don't mind at all.
Then wrap them in a thick hand towel to remove more water,then do the blow dry.
All my girls love being blow dried,you do need a cool setting,and don't have your hair dryer close to the bird.
My boys are typical boys,and dont want to be blow dried.So I put them in a dog cage and get them with the hair dryer there.
Mine are all pekin cockerels,so they plump themselves up,splutter and do a very good impresion of Captain Mannering from Dad's Army :lol: .