When you are looking to buy a dutch oven, look closely at the following items:
1. For outdoor cooking over charcoal briquettes only buy dutch ovens with legs. The ovens with flat bottoms are much more difficult to use. Legs lift the bottom of the oven up to accomodate hot coals. Flat bottom ovens have to be supported with bricks. Make sure the legs are not bent, cracked or broken.
Buy one like this... not like this.
2. Check the fit of the lid. It should fit flush around the entire oven with no large gaps. The lid should also have a lip that comes up above the top of the oven. This allows you to put coals on top without having them fall into the food. An oven with a rounded lid makes adding top heat very difficult.
4. Make sure the lid has a loop handle that is not cracked and is well attached.
5. Check the wire handle. It should be easy to move and strong enough to carry a heavy pot full of stew easily. I have an oven with handle problems. The handle actually comes off the oven--it makes it very difficult to move a hot oven full of food.
You also need to consider the size of oven you will need. They are avaliable in many sizes, 10", 12" and 14" are the most common. There are also standard and deep size ovens. If you are only buying one oven to get started, get a 12". It will hold just about anything you need. You can always add other sizes to your collection later.