I really enjoy getting up to the peace and quiet of the North Georgia mountains. Aside from my basic backpacking and camping essentials -- tent, cook gear, sleeping bag, and food -- my hiking boots are what get me to where I want to go. I've been through many a pair of them, so I feel comfortable in relating what I consider important in choosing hiking boots.
Read on, below the fold, for some of the things I know about buying hiking boots.
First off -- look for good boots at an outdoor/sporting goods store; you may find less expensive boots at a shoe store, but it's not likely they'll have the variety to serve your needs. As with most everything else, you get what you pay for.
Consider the type of hiking your want to do. Generally, the less rigorous the hike, the lighter weight and less sturdy the boot you will require. For long treks, rough terrain, or when hauling a heavy rucksack, you will have to increase the stability of your ankle support and (likely) the weight of your hiking boots.
A deep tread on the boot soles is certainly called for, especially if you plan to negotiate wet rock or loose surfaces. Make sure your hiking boots have a scree collar to keep the smaller rocks from getting into the tops of your boots.
A strong shank (the arch support), preferably fiberglass, is a must. If you can twist the hiking boot sole, with your hands, back away from that boot and look at another model.
Breathable boots, with leather uppers, are preferable. You want your feet to be able to stay as dry as possible, while at the same time providing support and protection. Look for hiking boots that are advertised as water-resistant, or water-proof (generally of all leather construction, and are some heavier.)
Look for hiking boots that have hooks for the top two or three lace crossings; that way, when the laces are wet or frozen, you won't have to thread the ends of the laces through eyelets that seem to have gotten impossibly small, during a 20 degree night. (Not that anything like that ever happened to me.)
Last, but not least of all -- when you go for your boots, wear the socks that you will wear on the trail, walk around for a few minutes, and not just on a flat surface. Try to replicate the ups and downs of the trail -- think stairs.
Before your hike, put some miles on your hiking boots to break them in. Once on the trail, it's too late to find that your boots are the wrong size and, instead of providing great support, only give you sore feet and blisters.