Even if you aren’t prepared to personally counsel women heading for the clinic, you can support sidewalk counselors with your physical presence. They often spend long hours on the sidewalk with periods of no interaction, so you can provide company. If there is only one counselor, he or she may not want to leave the sidewalk for fear of being absent when a woman approaches, so can serve as a runner to get food and drink or other supplies. If they are counseling in front of a particularly active clinic or one in a more contentious area, your presence may improve their safety (safety in numbers) or ensure they have a witness in the case of any run-ins with clinic escorts, counter protestors, or police. Standing with counselors (literally) is a simple but important way to support them.
Review a summary of ways to support sidewalk counselors here.