You are on the right track. I think you are probably in a good position to do this type of work more than you think. Approaching people, making return visits on them, following up on interest; those are things I'm sure you can handle.
A trick that I have learned to get past the gatekeeper is to follow this little list:
1. Call the prospect on the phone. Ask to speak to the person who is responsible for taking care of the carpet cleaning for the building.
1A. Expect that the person you speak to is not going to put you in touch with the decision-maker. That is their job as the gatekeeper.
2. Ask the gatekeeper if you can mail the decision-maker some information. (Normally they will say yes.) Now ask for that person's name. (Normally they will give it to you.)
3. Now mail the person who is responsible for the carpet cleaning some information about your services, and how you plan to help them maximize their carpet's appearance.
4. A week later call the decision-maker back. You can normally get past the gatekeeper on this call. How? Because you're going to ask for the person who is responsible for carpet cleaning by name. And you're going to tell the gatekeeper that you just sent the decision-maker some information regarding carpet cleaning. So the gatekeeper will assume that the decision-maker wants to speak with you, since you have sent them information that they'd be interested in and so they'd normally want to speak with you about it. This can generally get you through to the person you need to speak with.
5. Once you finally get the decision-maker on the phone, make plans with him or her to come in and do a presentation.
5A. On my initial visit, I personally like to use a PowerPoint style presentation printed out on a flipchart. I'll run through that flipchart presentation rather quickly with the decision-maker.
5B. I will also perform a thorough carpet inspection on that initial visit, and fill out a corresponding form for them. (The carpet Inspection Form adds value in the prospect's eyes, helping them to see that we are professionals and that we are there to help them.)
5C. I will also do a demo cleaning on that visit.
5D. And lastly I will write up a proposal and/or a contract.
That's a quick overview of how I have been successful in getting in front of the decision-maker. This is useful for accounts that you really want to get in front of. You'll also want to continue to make calls on the person. Be persistent! Make plenty of return visits. This prospect has the potential to become a steady income revenue generator for your business. It's worth your while to hold on tenaciously and continue to follow up on the interest. In following this little format that I've shared with you here, it will make it easier for you to get in front of the decision-maker and make commercial sales.
My last advice is to just get out there and GO FOR IT! It's been said that the hardest door to go through is your own. So set aside a specific day of the week for sales, perhaps Wednesday mornings, and stick to it. Kick yourself in the butt if you have to. The commercial world can be your oyster. There's gold in them there buildings.