Welcome to the forum,
I think I'll address those questions in reverse as the second one has a bit more straightforward of an answer.
First figure out what treats really drive her wild. For Auggie I have some dried blueberries and dried papayas which are his favorites. He really goes crazy for them and would do anything to get them. Its good to have a variety of enticing treats so some of them can be reserved for particular behaviors. In my case Auggie only gets a blueberry when he goes back into his cage on command.
In addition to finding the right reward you should consider routine, birds are masters of figuring out daily routines, often so much so that they end up knowing what we're going to do before we do. Use this to your advantage.
Every morning I spend a good bit of time with Auggie while I have breakfast, check emails, and stop in on the forums here. When I have to leave for work though he used to really make a fuss, and sometimes he still does - he has a knack of tucking himself away in a shirt pocket at the last minute hoping I'll take him with me.
I taught Auggie a command "go to your house" through blatant bribery with blueberries. I'd bring him over to his cage, give the command, then lure him in with the blueberry. I'd lure him over to one of his perches, close the door, then only give him the blueberry THROUGH the cage at that one perch. I was amazed at how quickly he learned the command. If I tell him to go to his house now he's at that perch in a flash waiting for the blueberry.
In addition however I clean and refill his water bowl right before I leave in the morning. He's figured this out so now as soon as I change his water he runs into his cage and waits for the blueberry. It's pretty handy having him know the routine.
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As far as other training just let us know what you'd liker her to know - to do - to not do. I don't know if there are any standard behaviors for birds for 'basic training' like there are for dogs for example. Perhaps the only one is the "step up" command. If your B&G does not yet do this well we could discuss that. Let me know.
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Now, on to accepting your girlfriend. The easiest way to do that is to let them interact. Have your girlfriend give your bird (What's the B&G's name?) treats. Have your girlfriend do some of the training with her - perhaps she could run the training for the command to go to the cage.
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As far as websites and good books for training.... well in a career of animal training (almost exclusively with dogs, cats, and some other mammals - limited bird experience) I have yet to find a training book I would recommend. Training is an interactive process, you need to work with a trainer so you can ask questions and get feedback. Methods need to be tailored to the situation and books are not very good at accomplishing this.
Of course I could recommend a libraries worth of books if you want to educate yourself on the entire field of animal training, but for a go-to book that will help you train your bird I'm skeptical if such a thing exists.
The website recommendation is easy. There's this great website called ParrotForums.com
Though if you want just some great books about parrots there are plenty available. Irene Pepperberg's are worth a look (The Alex Files, Alex & Me).