Forbidden Forest

"The Forbidden Forest, home to evil creatures and evildoers of all sorts.

''Along most paths, the forest's thick foliage reduces your visibility to only a few yards. The paths would be imperceptible except for your trained eye. You move as silently as a soft breeze across the thick moss covering the ground, wary to avoid stepping on a twig or any of the numerous pieces of bleached bone that populate the forest floor, lest you betray your presence to one of the vile beasts that wander the forest."''

The Forbidden Forest is the number one source of earning experience. To fight, you must choose between these three options:

Look for Something to Kill

Go Slumming

Go Thrillseeking

Fighting
You can earn experience by choosing one of the three fighting options. "Go Thrillseeking" will give you the most experience (and gold), but will be harder to kill. You have a much higher chance of being killed in this fight.

"Look for something to Kill" will put you up against a creature of your same level. Ocassionally you will find a creature that is a level below or above you with this option, but it is your best bet if you don't have any buffs and want to make decent experience.

"Go Slumming" is an option for those who REALLY just don't want to die. You will be fighting creatures of lower level than you, making the fight easier, but you will be rewarded less gold and less experience.

Goblin Banking
In the forbidden forest, you have the option to deposit all gold. While you will always see this option, it will only work if you do not owe any money to Gringotts. Once you click "deposit all gold" you will remain in the forest, but your gold will automatically be deposited into gringotts bank, no need to waste a travel point. Make sure that you fully heal yourself before you deposit your gold, however, or you may find yourself making unnecessary trips to the bank and back. Note that the goblins do take a 10% convenience fee for their services(rounded up)