i found with nut, keeping her mainly in the living room and sitting about watching telly etc and every now an again offer her a treat where she has to come to us for it, she would take treat an then fly of to top of her cage, once she got familar with the room (door kept shut) she was more confidant with us, and when we went to eat dinner she could come to the kitchen, but i put her into her sleeping cage now thats in the kitchen, so its dinner then taken upstairs to spare bedroom and covered, for her thats her night routine, but i would get her to perch onto my shoulder to go from room to room, i would stand at the door an say *come on nut, and she will think about it for a bit, then come onto my shoulder an i'll walk her into other room that way, and other times she wont want to come so she stays in the living room
also because we kept her mainly in the room with her main cage, she tends to toilet mainly over it

and if she is on me she will fly to the cage for a quick poop, and then back
i had probs getting her to bath, but she like to sit on my shoulder when i bath, so i so i splash her wet there

so if you can see what your birds reaction to water is? and speak to your birds previous carer about these things first
you say your bird gets low an shows the beak?? normally nut wont do that unless she is about to attack with intent! as her first signal of i dont want to is to lean away, turn her back, walk away and then she does the crouching tiger thing an with a hiss as well!! i didnt read these signals she gave me at 1st and i got bit rather a few times an once with blood

it got to the point when she just lunged when anyone went near her
Parrot Musings: Parrot body language
but now she knows she can trust me to understand her and she kinda knows our routines, but i still have days when she is a complete nut, but the biting has stopped, she just gives very gentle beak clamps, her fav person is my partner, i spend most time with her and the one she bites the most now is my son who ignores her signals
your bird will learn your routine, and as mentioned above, a vet visit for a check up and don't rush into contact
i don't think my nut will ever talk, but she does meow, this is because when i nip out for a cig, there is a cat that comes over meowing for a head rub so she must have heard it grrrr oh an she kinda makes a laughing noise at times
i've had days when i've been telling my son of for annoying her, only for her to start annoying my son and vise versa, she is like a 2yr old with attitude! its taken over a month for me to get to this comfortable with each other stage and even now certain things i take for granted will freak her out, like black nail varnish, new bits of furniture, or if she is in a mood about something and i put my hands into her cage for what ever reason, she'll be in to give me a nip
so use food to get your bird to trust you more, as i generally kept the best treats for making her come to me or getting her into her cage
good luck an let us know how you get on