Drive past Islip Saddle until you see a locked gate on the right side of the road. Park your car, there should be a turnout near there. Hike up the road until you get into Little Jimmy Springs. Once in the campground, take the trail marked Mount Islip. This trail will take you all the way to the top. Return on the same trail.
Although this route is slightly shorter, it still has about the same elevation gain. The road and the trail are well maintained. Overall, this route is easy to moderate.
Be sure to wear adequate hiking boots and bring plenty of water. Those are the essentials of any hike.