Yes they will coil like they are about to attack. And they will bite. But they are not poisonous. They do but off a very bad smell when they are scared as well. So try to just back away easily,,but even if they do bite there is no venoum in there fangs
I have a Blue Stripe Garter Snake that my husband caught under our house, and she did not bite when he picker her up. She behaved just as a rat or corn snake would when picked up from a tank in a pet store. They usually will allow you to pick them up. They don't even really strike at their prey much, they just bite it and swallow it practically still alive! It's amazing to watch her eat... We feed her minnows. Yeah... Well, good luck and I hope I helped!
Garter Snakes do not generally coild as if to strike. In fact, they do not generally strike humans at all. Although garter snakes have been known to bite if handled, mostly they just secrete a foul-smelling fluid from anal glands when alarmed.