Check your state laws. In some states (TN) it is against the law to kill ANY snake.
YEA for TN!!!
I'm a snake lover, and we have 5, all non-venomous. Most encounters with a snake in the wild do NOT need to end in a killing (on either side). The snake is MUCH more afraid of you than you of it. Look at it from the snake's point. Here's a BIG mammal (read "predator") getting REALLY close, I'm in danger. The snake has a limited amount of venom. It doesn't want to waste it on something too large to eat (you). He will only bite, and then only inject, as an absolute LAST resort to make you go away.
From your point, here's a small reptile who can only harm you if it's within striking distance (about 1/3 body length). For most NA snakes, that's about 2', maximum.
In the woods, wear heavy leather shoes or boots. KEEP YOUR EYES OPEN. Stumbling upon or stepping on a snake is the best way of getting bitten. Do NOT reach into any dark or confined space unless you can clearly see what's in there. Wherever you reach, look FIRST. Beware of sunny spots on rocks or leafy ground cover. Snakes love both. Snakes will be most active at midday, when it's warmest.
If you see a snake, FREEZE! Back away SLOWLY. Don't stomp around. The snake can feel the vibrations through the ground and may become agitated. Always assume ANY snake is venomous. Sometimes a venomous snake's coloring mimics a harmless species.
If you ARE bitten. Call for medical help immediately. Quick treatment is your best chance. If the snake is crawling away or you're out of striking range, DON'T shoot it. It won't help you any. Bandage the wound loosely and place the bitten area lower than the heart. Remain calm, don't run around. Watch for, and treat for shock. Apply a loose tourniquet between the bitten area and the heart, as close to the bitten area as possible. Do not cut the fang marks and attempt to suck out the venom. Every little venom remains close enough to the surface to suck out. If you have a raw spot or open sore in your mouth, now you're in trouble, too.
Venomous snakes in NA are:
Rattlesnakes (various species) - Bite may be fatal
Coral snakes - Bite seldom fatal (short, rear fangs)
Cottonmouths - Bite possibly fatal
Copperheads - Bite seldom fatal
Enjoy the woods, but keep your wits about you.