Get the strongest pepper spray you can find and if you need to use it use plenty of it.

Some time ago I was reading an article that suggested that too frequent, and ineffective exposure to pepper spray has allowed some bears to develop a taste for food spiced with pepper spray. Knowing my luck I would get the grizzly that likes his hikers extra spicy. I guess that once I recognized that the bear likes the spray, assuming I lived that long, I could spray another hiker and run.