Glacier is freaking gorgeous. It's gonna blow you away, (and no, your photos will NEVER do it justice) but jhkayakr is right. Montana is grizzly country, and if you don't take that seriously, you could find yourself in a lot of trouble.
Keep the food in sealed bags and containers - doublebagged ziploc bags that won't let the smell out. Never have ANY food or enticing smells (deodorant, perfume, toothpaste, chapstick, water bottles, etc) in or near your tent. Never sleep in the same clothes you cook in. Change outside your tent and do not bring the cooking clothes in your tent. If a bear smells them in your tent, he won't know the difference between that and real food, and he'll come looking for it.
Cook fires should be at least 100 yards away from your tent (farther if you can), and you need to invest in a bear canister. It's collapsible (the titanium ones are the best 'cause they're lightest). You put all your food in it at night, then suspend it from a tree a minimum of 10 feet in the air.
Don't worry about the bear bells a lot of people wear on their ankles - they don't work and they just make you look and sound like one of Santa's elves
It is a good idea to talk loudly though, and if you do see a bear, don't stare at it (it will see that as a threat) and slowly back off until its out of sight and then get out of the area. Never run from a bear. First off, they're a hell of a lot faster than you, and second, when you run, you're acting like prey.
Also, if you come across any carcasses, get out of the area immediately, and be very alert. Bears sometimes store carcasses and feed on them for days - and they'll interpret your presence as a threat to their meal.
If a bear attacks, get out your pepper spray. This should be specifically grizzly pepper spray - it's a big can, always have it handy on your belt. Spray the bear in the eyes. If that doesn't work, curl up into a ball, don't stick any limbs out, and try to protect your vitals while staying as still as possible. If the bear keeps mauling you, you may have to fight - use anything you have handy. . . knife, hatchet, whatever, and give it your all.
With all that said, keep in mind that grizzly encounters are extremely rare - you probably won't even see one - - I haven't any of the times I've been to Glacier, Teton, or Yellowstone, much to my disappointment, so it's not like you need to be terrified your whole trip.
Above all, have a blast and tell us how it was when you get back!