Pretend like your running for office. Shake hands introduce yourself. Let them know about your business and why they should be choosing you over the other guy. Smaller business, more personalized attention, owner on every job. Those kinds of things help but the biggest thing is PRICE!! Hope this helps!
People buy from people they know. The most successful way I have seen to land commercial accounts is to knock on doors and find out who is in charge of the building's property maintenance. Then find out when they accept bids. The more people you talk to the better.
I think what you are running into is a reason why many LCOs tend to stick with residential customers. It is very difficult to market to commercial establishments. It takes time to cultivate relationships with commercial property managers. Also the return sometime isn't worth the energy put into it.
But remember you can do it. You can make it happen.