How to get big commercial accounts

Doing commercial work in my back round is better/easier. The pay may be net 30 witch isn't fun sometimes. I suggest just going in talking to who ever is in charge about what you would like to provide. Just really don't be afraid to go talk to people and building a condition with. Find out when others contracts are up and note that for when the contract is up.  Also get name and email and phone number to follow up with.

You may want to consider government contracts in your state nd local areas. I actually help my clients get set up to secure some of those contracts and depending on what area you are in, they may be more frecuent in how often those services are procured.

I would join commerial organizations with property and faciltiies managers. We joined CAI, IREM, BOMA, Apartment Association, IFMA and more. This has given us the ability to become 70% Commercial for our exterior cleaning company. I would also build out a commercial page on your website. 

I would suggest testing that market out first by setting up 1-2 accounts at a discounted rate to see if it's something thats within your service offering. When you mix markets, you almost end up running (2) separate companies believe it or not. 
We stopped doing commercial work years ago because we were spending too much money trying to crack into a completely different market. Just a suggestion.!

If you are asking how to get them specifically, cold emails/cold calls to facilities titles or property managers is the most direct route to starting conversations with them. 

I find that commercial clients don’t simply want better pricing; they want better/frictionless service. If you sell yourself as reliable, easy to communicate with, proactive and can come in just a few dollars less, you’ll be an enticing consideration. 
Ask the potential client what their current provider could do better. If you can realistically improve on the pain points, clearly articulate why and how. 

In person meetings can be problematic as everyone is busy. Offering a freebie or discounted service to a client at a large complex can be the best advertising you can get. But you’ll need to have your game face on while on site. 

There are several 3rd party National companies for commercial work.  You must have WC, Comm Auto and General Liability.   DMG is one of them.  Case, and MSA.