This is how I do it.
Walk in store, you should have your pricing down so that if you had to you could give a price as you walked in.
"How can I help you?"
"I'm looking for a manager or an owner."
The peon at the front usually wanders back and calls to the manager. "Gary, there is some guy here for you"
or they may say "What is this for?" (Keep in mind they have no decision power, they are peons, they are just asking..."
"I'm a professional window cleaner" They usually say "ok" or they may throw an objection like "We already have someone" or "We actually have our property manager do that stuff"
I say "That's fine, I'd still like to speak with a manager"
Let's pretend Gary walks up to the desk.
"How can I help you?"..
Hi, my name is Alex, I was just in the area putting quotes on windows and I am wondering if you would like a free bid?
"Well we already have someone"
That's fine, a good window cleaner is hard to find. Can I still leave my quote?
I walk outside, my minimum bid is $12 for the outside. Some guys are $15. It depends.
Go back inside "Ok here is my quote for today" I show them the card, tell them the price, give them the card. I also say I wipe down the sides (I point to the sides of the windows where the rubber is), I also point to the metal base-plates and say "I wipe these down too". I am smiling and trying to be confident. I also say "I will make them look brand new"
"Does that sound like something that you are interested in? I can do it today!"
This is the ultimate sale moment! ASK FOR THE SALE! Please ask for it. Don't leave a card, ask for the sale!
"Umm well I would have to speak with the owner..."
And then I check back in 2 days. Because eventually Gary will wear down and give in to me.