The Redwoods consists of three spawn zones, starting in the north and heading south. The area gets more difficult the closer you get to Redwoods Zone 3.
Moving south from Twin Peaks, you reach the end of the first large lake. Follow the path to the second lake, which is in Zone 3. As you continue south, you'll encounter the first of the old stone bridges. This is a good spot for a base, as dinos continuously spawn in the falls here, or fall from the upper falls. They're easy to kill for resources. This is also a good spot to train Pteranodons.
When you continue south, moving up the hill from the old stone bridge, you'll find a rich area of metal, obsidian, and crystal. Also, in the river by the old stone bridge you'll find rich metal resources.