The Forks of the Kern trailhead is your staging area for loading your gear for your hike into the Forks. There is plenty of parking here, a vault toilet, and camping areas. For those doing a bullet run a common strategy is to drive up the evening before your trip, camp here, and then early the next morning, get started down the trail and to the river. This will give you a considerable jump on the day compared to trying to do everything from Kernville the day of.
While packing for your trip be mindful of your gear before driving up here. There are no amenities or cell phone service nearby so the opportunity for taking care of last-minute items does not exist, so your gear item checklist should happen prior to leaving your garage, and not before heading down the trail.
The trail itself is well marked and almost entirely all downhill. What makes it challenging is determined by how much gear you are carrying.
When you get to the bottom, cross the Little Kern to get to the island. On the left side of the island is where it is easiest to put-in.