To get to the trail head take Sonoma highway 12 to Los Alamos road (it is clearly marked) approximately 6 miles, it will turn into Timberline Drive, take it to the trail head.
Take the Goodspeed trail marked on the left side of the road. You will go over a foot bridge then double track along the creek and upward. As you ascend there are views of the Sonoma Valley (Kenwood and Glen Ellen), the trail skirts the creek and crosses it again, then turns into single track, you will leave the cover of the forest and walk a narrow path along the side of the mountain, at the top of this climb the trail veers to the left to Gunsight rock. Once at the top you will find panoramic valley views and of course Gunsite rock at your feet
the best time of year is Spring, early summer or fall, bring a hat during hot days, layers during cooler months, at least 3 liters of water, good hiking shoes, there can be ticks here so long sleeves are a good idea.