There are no snakes allowed in the BNC, unless they pay their $3 entry fee. If you go this Sunday, entry is free since it's the first Sunday of the month! The bad news is, snakes and other riff-raff also get in free.
Here is a pretty good map that Thot made, showing the area with caches, trails marked, and where you can drive vs where you can walk or bike. A bike comes in pretty handy, especially in warmer months.
You can get a lot of caches by following the trails with short bushwhacks. For most there is a fairly easy way to get to them (because I don't like bushwhacking either!), so read the cache description for pointers. A few (Room with a View, For the Birds, Evergreens, Cactus..... oh, and Brute Force) require a bit more work to get to. There is a Challenge cache in the park for getting 6 cache types in a day. There are 6 cache types in the park itself and another virtual that is visible from there about 2 miles to the west. If you are planning to do the Wherigo, make sure you load it up on a playable device (if it's a smartphone, make sure Location Services is enabled for that app!). It really helps if you can play it on a device you are NOT using as your primary cache-finding device (so you can grab other caches while the cartridge is running).
To maximize your caching efficiency, do this: Start with the Earthcache -- get the needed info at the visitor's center and the posted coords. Grab the other nearby caches as you work your way to the west end of San Jacinto Point. Start the Wherigo cart while out there near it's listed coords. Head south, grabbing other caches as you head to the last stop for the Earthcache at Brownwood Pavilion. From there, the Wherigo will take you on a clockwise loop around the south end of the park. You can make other small detours and grab caches along the way. Sign the log for the Challenge cache while you're down there. At the final stop for the Wherigo, it will display the coordinates for the cache in a screen. WRITE THESE DOWN. If you're using your phone, take a screenshot of them. You can then finish caching in the park and grab the Wherigo cache itself on the way out of the park.
Read the logs for my BNC-For the Birds cache. There is a new trail under construction that eliminates about 200' of bushwhacking!
Last of all -- Have FUN!