- Bears: You still need to be disciplined about food/smellables. Bear canisters are required for most of the Sierra—not bringing one is a recipe for a fine or getting escorted out by a ranger. Also, other critters are a problem. I had a raccoon steal my unguarded shorts (they had a bag of weed in the pocket) while I was sleeping, and I had to walk back to town with no pants.
- Logistics: Bishop/Kearsarge passes are quite remote and rugged, and then you’re on the PCT/JMT superhighway which is increasingly over-stressed by people. You can enter via Duck Pass or Red’s Meadow from Mammoth Lakes via public transit. The friendliest place for beginners would probably be further north in the Lake Tahoe region (e.g. Tahoe Rim Trail). Vermillion Valley Resort is a (rugged) ~1 hour drive from Fresno, and is one of the most classic congregation spots for PCT/JMT hikers and would make a great entry point. Angeles National Forest / the PCT would be a good choice for the LA area.
- Lightning/weather: The weather doesn’t care if it intimidates you or not, so you need to be prepared for anything. I didn’t bring rain pants to the desert section of the PCT and got slammed by freezing rain and had to run to avoid hypothermia. Also, please don’t do something batshit insane like go over a pass in inclement weather (I see it all the time). Here’s a document on lightning safety: https://www.nols.edu/media/filer_public/fa/96/fa96d71d-df6b-...
- Leave no trace: The Sierra is heavily impacted, so please tread lightly! In particular, don’t camp <100ft of the trail or a body of water, use Bluetooth speakers, or leave toilet paper blooms (packing it out is recommended but has low compliance, so at least mash up the TP and waste with a stick and some water to make a soupy mixture—critters like to dig up the lightly used paper). Being a wilderness ninja is cool, so read more LNT guidelines here: https://www.rei.com/learn/expert-advice/leave-no-trace.html