Let’s consider what makes a good, safe construction site. Sure there are the basics like hard hats and temporary traffic cones and things so the trucks and tractors can move about the job site safely, but think more than that. First think about what kind of construction site it is. Some jobs are erecting a building while others might just be underground pipes and electrical matters. Each job site is a bit different, a bit unique, and each job site requires safety precautions.
Temporary fencing from the folks at http://www.tri-citytempfence.com/temporary-fencing-escondido-ca.html make fencing easy. Your job site should be enclosed so that it is clear to the public what sections are under construction and what sections are not. There literally should be a line or a fence that distinguishes this difference. Caution type might be an option as well, but that is typically for smaller job sites.
No matter what the job site looks like, safety most definitely comes first. Do what it takes to ensure a safe work environment.