Part of having a yard is dealing with all of the critters that will wander over to visit you. Some of these will be cute and fury, and others will be more scaly.
Most of the time, garter snakes don't pose a problem at all. Snakes are elusive creatures, and they disappear like ghostly apparitions because they can feel the vibrations of your steps from very far away. Your neighborhood garter snakes will do everything they can to avoid people.