There are a lot of nice training tips in this thread!
She may also be a bit sensitive about getting her head since she snapped when her collar was pulled on. You could try this, too (along with all the other excellent advice):
Put peanut butter (a light layer) between several fingers
show her your hands & let her sniff/lick them - you want your hands to be associated with good things - especially around her face. When you can put your hands up to her face without her flinching or any sort of aggression & she is actively bumping your hands looking for treats (when they aren't covered in PB) - progress to this:
put a treat in one hand near her nose & rub the other hand along & all over her muzzle (like a face massage after a long day at work - yum!) - if she lets you do the massage without fuss, give her the treat (do this several times a day) - when she tolerates that, move to this:
keep a treat in one hand near her nose & start moving the hand giving her the face massage towards her ears & jowl - again, treat for her letting you move your hand all over her head without fussing & progress to this:
keep a treat in one hand near her nose & massage until you can put your hand on her collar - don't try to "grab" the collar yet - just move it like you are going to adjust it on her neck & pet/massage all over her neck - as always- treat for good behavior; then progress:
treat in one hand; massage; grasp collar & lenghthen the amount of time you have a hold of it - treat for good behavior (You may even want to go one step farther & start walking one or two steps while holding the collar - it really depends on you & her & how far you think you need to go with this to teach her that you are allowed not only to touch her face, her neck, her collar, and to hold it while she is walking.)
give a jack-pot (which is - lots of treats for each 1st & 2nd time she lets you do any of the above) & of course, lots of verbal praise!
hopefullly it'll get her where you can get a hold of her collar - a necessary thing - without her going ballistic;
and it'll help her with being "head-shy" - many dogs see our hands as tools of aggression (unfortunately) & need to learn that they are also capable of giving great pleasure......
...always start your petting around her face under her chin - as she gets used to that, move to petting on-top of her head - ask your friends/strangers that want to pet the pretty BWD - to do the same, let her sniff their hand first, then start to pet under the chin before they go on-top of her head, so she doesn't see their hands as aggressive either. (Be sure to desensitize her to being petted on her head as she looses her head-shy tendencies)
I like the idea of getting her to go into her crate by leading her with a leash - Casper is my only dog that wont willingly go in the crate - I have to put a leash on him & lead him in there or we'll be playing chase in order to get near & hold onto his collar, & then tug of war (not good when he weighs 90lb!) to get him into the crate!
I also make their crates available so if the dogs are tired they can go in & curl up for a nap any time during the day - and when I do have to put them in their for long periods, I put chew toys (some rubber, some soft, sometimes Kongs stuffed with goodies) in there with them & always give them a treat for going into thier crates. I feed them in their crates, too - (except Casper who really doesn't have a crate of his own - just borrows from the others when I need him contained). I have a pet sitter that comes & lets them out half way through the time I'm gone at work so they don't have to spend extraordinary amounts of time sleeping or being bored in the crates.
Frosty became very destructive after a month of being crated - at first she liked the crate - she is so shy I think it made her feel safe, then she developed a devilish desire to eat through the wires (she was raised initially on a goat farm, albeit an abusive one) - she destroyed everything soft I put in there for her to lie on, then ate the plastic pan liner & chewed a fist size hole in the carpet & pad after eating thru the liner. Now I just leave the door open - she goes in & out at will. The only time she's in there with the door shut is during feeding - she & Bella would growl & snap & be food protective (it happens when you've been a starved doggie for too long) - and feeding everyone in their crates (except Casper) solved the issue. She has not been destructive with the door left open except for my bad habit of leaving papers/magazines on the couch - she will snag them & tear them up for me.
Getting her a job of guarding "something" will help, too - dogs are pack animals, I think they do better if they have a companion to play with - have you considered adding another dog? Or even a dog-friendly cat?
Best of luck!
-lauriew