These are some notes I took following a conversation with the staff at a local dog training organization:

• If your dog is anxious or agitated around strangers, you need to slowly acclimate her to being around other people.
• Do not reenforce fearful behavior. If she jumps up on you or cowers around you, she is seeking confidence and reassurance from you. It’s best to ignore her in these situations, or instruct her to do something else that she has learned to do on command. It’s only okay for her to jump up on you if you say it’s okay, not just any time she wants.
• Around strangers, if she becomes agitated, keep her on a short leash: an inch or so of slack is enough for her to learn that she should prefer staying right next to you instead of running away from or toward the other people.
• Have your house guests throw her treats from a distance, so she learns to associate visitors with treats. Preferably use high quality, high value treats that she especially enjoys (but rarely gets).
• Do not exhibit fear or anxiety yourself; she will pick up on that, and she needs you to be a strong leader.
• If she gets out of control around other people walking on the sidewalk, try to practice that on purpose rather than avoid it. Preferably get her around people on the sidewalk who are walking away from her, rather than toward her. They will still be in the vicinity, but less threatening.
• Some of her behavior may be related to natural herding instinct. Unless you plan to put her into service as a sheepdog, it’s best to train that out of her, as much as possible.
• One benefit of her herding instinct is that she protects the herd. Once she accepts someone into her herd, they become someone she protects, not someone she fears.