I've hiked many miles and spent many nights in black bear country. I've never seen one other than crossing a forest road on my way to a trailhead, but twice I've heard what sounded like a bear in the distance. As for preparing, I always exercise awareness when hiking and secure my food when camping.
Other than ticks (I hate them!) my only encounters with dangerous critters were a small rattlesnake that struck at me but came up short in Red River Gorge, and being rudely awakened near the Rockcastle Narrows (also in Ky) by a pack of feral pigs. I was asleep in my Warbonnet Blackbird hammock at 4am when I heard the most godawful noises close by. Almost immediately I perceived what they were, but was still in shock mode when I tried to shout but nothing came out. I forced myself to relax, took a deep breath, then loudly yelled YOU GET OUTTA HERE YOU PIGS!!! They made screaming noises, then quickly skedaddled.