Do your homework to find out what kind of wildlife is in the area where you will be hiking and what to do if you come in close contact with something. Pepper spray or bear spray in areas with bears. Black bears are not too much of a threat. Grizzlies are another matter (don't play dead!
). For snakes and/or spiders, don't put your hands anywhere you can't see (behind rocks, logs, etc). Know which snakes/spiders are poisonous and what they look like, in case you do get bit so they can give you the right treatment for that particular snake. Cougars are pretty elusive but what ever you do, DON'T RUN!! They will automatically chase you and you won't get far. Just look as big as you can and throw things at them.
Don't leave food around, especially at night.
When I lived in California, I did quite a bit of hiking and some camping and even tho there are warnings all over about rattlesnakes and cougars, I never saw any signs of either. And I only saw one coyote (crossing a road), so they generally stay hidden. Just be aware of your surroundings and enjoy the scenery!
For weather, get a portable weather radio to keep with you so you can always check the weather where you are. Common sense is useful here. Don't hang out in low areas after a heavy rain, don't wash the roof of your RV during a lightning storm, don't stay in your RV if there is a tornado coming, etc. Be prepared, not scared.