I've spot and stalked several bears in the Golden State over the years. Many have been at timberline areas in the Northern portion of the state, but I've also bowhunted them in timbered or sage type areas in the Sierras and Southern Cal mountains. I've never hunted them with dogs, but I imagine that method is probably the most reliable. Key to hunting them with any style is locating areas with a lot of sign.
Here's some photos of a P&Y caliber black bear I stalked in on in the Sierras (X-12). Wish it was a week later in the month, I would have arrowed him at 12 yards.
Hunt them the same way you would deer for spot and stalk.
Most bears I have seen in the D3-5 area's like the thick, cool timber canyons during the day (never hunted them above timber line). If you find such a canyon (with bear sign as BOHNTR stated) glass it a lot at first and last light.
When they come into season, hunt the areas with the salmon berries. The bears love these little berries. I have seen them hit the berries at all times of the day light hours. You will notice their scat more because the berries give them the runs.