How do I get cleaning bids

They are listed in newspapers. It is usually of public record. Other then that I don't know.

Cold call, knock on doors, talk to people, get referrals, pass out calling cards/brochures, etc.

Plus public bidding as mentioned above. Although you will be startled when you see how many other bidders there are. Some companies survive on this type of business. But normally it is low ball business.

Smaller companies/businesses are a good source for new cleaning companies. And better profit margins.