West Brecilian Forest
The problem here is that it seems like the forest is a little random. There also isn't much special for fighting the enemies in here. Werewolves and bears are just standard enemies. Just slash your way through them. If you've got a healer, then it's pretty easy for the most part. The ogres and wild sylvan can be hard since they can incapacitate members of your party, but as long as they don't stun your healers you will be fine.
Look around the starting area for the wounded elf. We might as well get that side quest out of the way.
Move along the rough path to the left. You should run into some wolves and werewolves. Just cut right through them. When you make it to the waterfall, you'll run into Swiftrunner. Some persuasion will let you avoid a fight here. If it does come to blows, then just wound Swiftrunner until he retreats.
There's a bear you can kill nearby to get some loot from a dead templar. After that, just keep moving along the trail further east into the forest. There should be some darkspawn and an ogre by the tombstone up ahead. If you're doing the Places of Power quest, then touch it to place the marker. This tombstone is also part of the Mage's Treasure quest that will net us some juggernaught armor. We need to start that in the East Brecilian Forest though.
I suggest that you go a bit further and down the path. Go ahead and talk to the Grand Oak now. You'll need to kill some Wild sylvans along the way. Just take it slow and steady and you'll be fine. Remember that you can apparently backstab a tree, so put your rogue to good use.
While you're here, you should also save and then go a little past the Grand Oak to the camp. This is a big trap and you might get killed if you're not careful. It's all an illusion from a greater shade. Don't examine too much in the camp, or it will lull you into a deep sleep. Trying to leave and demanding to turn around and look at the camp seems to work well. Mages will also usually be able to resist the temptation to fall asleep and be attacked. It appears that there is a willpower or magic check. It was easy for me, since I just had Wynne cast revival and it brought everyone back to life.
The greater shade itself isn't that dangerous, especially if your party is still alive. Just surround him and attack. He'll die pretty quickly.
Make sure you grab the dusk ring off of his body and loot the chest and bones around the area. We can trade the ring later and the general loot is pretty good. There's also some Dalish Gloves that you can give to Zevran as a gift.
Check the area a little more and when you're ready to go, take either exit to the East Brecilian Forest.