Here's what I've done every time I've gone to grizzly/brown bear country and will continue to do so.

Remember that they can cover 10 yards in 1 second while moving in 3D and they can also be ninja quiet.

1) Check your ego. Very few of us are actually as good as we pretend to be. Seriously.
2) Be realistic with your expectations of what you actually can do. For example, most of us tend to be better served with a 9mm than a 454 Casul.
3) Practice getting off very fast, very accurate (CNS), and (eventually) multiple shots with your primary weapon. Laser trainers are excellent for this (at least shot 1) especially when combined with a charging grizzly target. This includes un-shouldering the primary weapon, loading a round, acquiring the target and getting an accurate shot off. Do multiple variants of this (including turning around to find the target) and record your time. Ultimately this will tell you what your minimum buffer zone will be in the event that you surprise a grizzly. Hard to tell the GW that you were being charged and in fear when shooting the bear 100 yards away; we're talking 10-30 yards tops before you even have a thought of needing a weapon. Don't forget to send real bullets down range using multiple targets and shot timers. You should quickly identify which part of the shooting process is taking the longest and focus on reducing that time but never put accuracy on the back burner.
4) Repeat #3 with bear spray and/or handgun and adjust accordingly (ex: holster and not sling). Don't forget to send real bullets down range using multiple targets and shot timers. You should quickly identify which part of the shooting process is taking the longest and focus on reducing that time but never put accuracy on the back burner.
5) Use purpose built ammo if using a handgun. Forget your HP or ball ammo; use Buffalo Bore hard cast or comparable. Very important to ensure that your gun will shoot it. It's all about penetration to the CNS here.
6) Just like 2 legged boogey men, grizzly are not behind every tree. Be aware and respectful but do not be overtly fearful.
7) If you have to come back to a carcass, place a few tree branches in a vertical position over the carcass. If something of size came in, the branches will likely no longer be vertical and give you a heads up.
8) Always have a weapon on you or within arms reach. Doesn't matter if you are sleeping, taking a leak, taking a dump, cleaning an animal, packing an animal, etc. Remember 10 yards in 1 second. That weapon "over there" is worthless if a situation arises.
9) Understand that they literally can go from peaceful (ex: golden retriever mode) to full-blown apex predator hell bent on your destruction in a blink of an eye. Seen this first hand and is something that I will never forget. Never underestimate their ability to take damage when they are pissed; this is why the focus on CNS. They can be dead on their feet and still maul you to death or worse before they eventually give up the ghost.

Practice, practice, practice. My target timing for #3 is 1.5 seconds with 1 shot and #4 is 2 seconds with 3 shots; all at 90% CNS hit on the first shot while wearing a 50# pack over my binocular harness while wearing a Razco holster on my chest.

I've never hunted in bear country, but I would think I'd rather have a double action revolver than single action. When tenths of a second count, a single action is SLOOOOWWWW.

CNS = Central Nervous System