Ask any professional photographer the one thing they love the most - the one piece of equipment that they feel all warm and fuzzy about, the one thing they need more than anything else to make great photos - and you may be surprised at how many point to their tripod.
A tripod no longer needs to be the beast you remember your dad lugging around when you were a kid. It no longer needs to weigh a ton and take forever to unfurl or to fold back together.
What to Look for in a Tripod
The follow features come in handy and are ordered in rank of importance:
First and last, you need your three-legged friend to do the job for you. You need it to be stable and I would always consider this over cost, weight, etc. The funny thing is that the heavier the tripod is (within reason), the stronger of a bond you will develop with it. A strange connection and a bizarre gratitude will develop deep within, as soon as you see the improved results start pouring in from the lab.
Always a good feature, this allows you to quickly slap your camera body on the tripod or to whip it off in a hurry.
Example: You are driving along and you spot a spotted owl on a stop sign, eyeing a snake sunbathing on the shoulder. You stop and (if she hasn't flown already) you set up. Having to screw your camera on will usually keep you from doing it. You will most likely skip this step, lean against something, and do your best (we are only human). You get your pictures back and, guess what, your slow Velvia film has caused the camera-shake to be all too noticeable. If you had been able to slap the camera on the tripod in a jiffy, you might have got that shot and won the local county contest.
Example Two: You are right in the middle of an exciting shoot (portraits, still-life, you name it) and, although the creative side of your brain is screaming for free-flowing expression and spontaneity, the right side has attached your camera to a support of some kind and refuses to let go. If you had a quick release, you could compromise and be allowed to quickly remove the camera from the tripod for the occasional wild angle or creative shooting method.
As Much Height As Your Need
Don't rely on the extension pole in the middle on the tripod. If you will be shooting at eye-level often, get a tripod that extends the your eye-level.
For a good tall tripod with great stability and a convenient quick release feature, check out the Bogen 3021/3030 combination.
On the road? Or backpacking? Or, worst of all, flying with only carry-on (if you can help it)? A tripod that folds into a tight package will keep it convenient to use, and we all know how much of a part convenience plays in the actual-usage-to-closet-storage ratio.
The best of these compact tripods are:
Controls That Make Sense to You
What do you feel more comfortable with - the video game controls of a joystick or the level-headed 3-way pan-tilt head? Pick controls that are easy to change in a moment, where you don't have to look at what you are doing, and that seem intuitive to you.
Now that you know what to look for, go pick one out. If the thought of selecting a big professional tripod is overwhelming, at least dip your toes in with a beginner's version. Either way, you will be glad you did.