You simply knock and then enter if they won't respond.

I also did door knocking and use my sphere of influence etc..

Most of the threads I've found on door-knocking have focused on how to talk to potential sellers.I spent most of my college years doing both door-to-door and business-to-business sales, and I'm pretty familiar with all of the techniques for approaching a cold lead, building rapport, overcoming objections, getting rejected, asking for the close, etc. 

Even if high winds were to knock over a tree, unless the tree owner knew it was a danger, the owner of the land where it fell would be responsible for the cleanup. 

It is entertaining to watch a guy run through drywall and knock over cabinets with a sledgehammer.

So I ended up knocking off $250 per month from my monthly mortgage payment.

Another idea will be to drive around, knock on doors, get out of the car and talk to people.  

@David AveryA few days ago I knocked on the door an no one answered, although there were cars in the driveway.

You can knock $25 off her lease as a result of removing the storage room from the lease. 

Go out and start driving for dollars and cold call or knock on doors.