"What do experienced sales reps do starting out to make contacts and sales?"
An experienced sales rep entering a new market segment should initially become part of that segment. Join local security associations...each state will usually have its own association. Consider joining ASIS, and attend meetings to "rub elbows" with end users. Look into joining sales lead sharing groups, whose members are sales people in a wide variety of industries...printing, medical supplies, accounting services, etc.
Study the web sites of potential customers...you will be astonished at the information businesses put out about their go-to-market strategies, target customer segments, testimonials from satisfied customers, and bio's of their staff. If you are successful in getting an appointment in a larger firm, ask that person to give you a tour, and introduce you to other staff.
Put the word out on social media platforms. Exhibit at, or at least attend, local business-to-business shows and events. Consider joining the Better Business Bureau.
Lots of free advice on line.
Do lots of things in parallel, not in series.
Always get referrals from every contact you make, and testimonials from every customer. Consider asking a happy customer to not only let you use their name, but actually reach out to someone else. I have even asked customers to do this while I am in front of them...you will be surprised at how many happy, satisfied customers want to actually brag about how "smart" they were to use you, your products, and services. Early in my sales career, I actually had a short, prepared text ready, and asked a satisfied customer, once they said they would be glad to do a testimonial, if they were comfortable with my proposed language. Many times they laughed and did it right in front of me. People like to be sold (serviced) by professional courteous and even slightly aggressive sales reps. Most people have a built-in B.S. detector, so remember...a truly great sales experience is based upon great service, not slick trickery.
Lots of basics here, for sure, but you never know what might resonate with you and give you some starting points.
Good luck.