Try a different section of forest. It might not be as crowded in a different area. Sometimes when I walk through there it seems almost deserted.

Move carefully and listen for the sounds the mobs make. Greydwarves mutter a lot and trolls have a low groan. You can usually hear them before you see them. If you hear fighting noises then the skeletons and greys are fighting each other. (A good clue that there is either a crypt or a tower nearby.)

Don't go in at night. The spawns are more numerous and advanced then.

If you're mining or chopping trees and plan to stay there awhile, dig a pit and bounce them in there with your shield. The don't respawn if they don't die. *Daytime spawns only.

Trolls can't fit through tight spaces and they can't jump. They have to walk around any log that they knock down. They also can't cross steep sided ditches. Use this to slow them down or keep them away from you.