Most of us get our first experience night hiking when the sun sets before we get back to the car...
It's just like day, except it's dark. (Well, almost.) And maybe a little cooler.
Probably worth doing with others until you are comfortable.
You can see a lot better without lights than most people would think. If the sky is somewhat open above and there is any moonlight, one can hike pretty much any relatively easy trail. Particularly easy to do in winter when you are walking on a white carpet. It may take up to 1/2 hour for your eyes to adapt to the dark. Eat lots of carrots.
We (people from my college outing club) used to run a night hike up Monadnock via Pumpelly Tr. The goal was to leave the car after the sun set, summit, and return to the car before it rose--all without using our lights. (We, of course, carried lights.) It was very doable if there was a good moon (we scheduled for full).
Headlamps:
I carry 2 if with others or 3 if solo (caver's rule). One which can throw a good beam (eg, PTec Yukon HL or BD Zenix IQ) and one or two small LED lights (eg PTec Aurora, Petzl Tikka, BD Moonlight). The strong beams are rarely needed for hiking (I'd be comfortable without one on a known easy trail)--the low or medium intensity setting of an Aurora is generally adequate. (The strong beams are mainly needed for fast movement such as skiing down a slope or trail. Occasionally useful for navigation--eg checking out the trail at a distance.)
Big beams eat batteries. Lower intensity lights last longer. The recent multi-intensity LED lights are _very_ useful--you can choose the minimum intensity necessary for the job at hand and save the batteries. Use lithium batteries in winter or to save weight. IMO, LED lights rule--no bulbs to blow out and they still give good light as the batteries weaken.
I usually use an Aurora for hiking and camping and keep the spare and the big-beam light in reserve. The 2nd and 3rd lights give you light to fix the first by or just get you back to the car without worrying about the primary if it fails. The lightweight LED headlamps or pinch lights make great backups. (I have heard of ultra-lighters using just a pinch light...)
Using a headlamp:
Using the headlamp gives you tunnel vision--you see what you are pointing the light at and little else. (Broad beams help and I use one a lot more than I use a narrow beam. Turning the light off is even better if there is enough ambient light.) Depth perception isn't very good with the headlamp on your head--hold it in your hand to improve. Back reflection from fog, heavy snow, or brush is also a problem--again hold it in your hand.
One argument for using a headlamp under conditions of adequate ambient light would be to warn animals (and hunters) that you are coming. Save your bear and moose encounters for the daylight.
Headlamps also tend to attact insects to your face. A baseball cap helps.
Point of Etiquette:
Don't shine your headlamp in anyone else's face--it will blind him. When talking to someone, turn your head to the side. (Exception: a deaf person who is trying to read your lips may want to shine his light in your face.)
Doug