Red-sided garters as a rule are pretty agreeable. Females seem to be most inviting to becoming docile. I can't speak for T. e. vagrans(never kept them).

Food is a good way to breakdown fear. Using a pair of hemostats will help as it separates the food from the hand. Give them plenty of hides and put them in a place they can see you. This will get them used to seeing you and that you don't come after them all the time. They are not housed together are they?