Yep i did it many moons ago for double glazing
I am still in sales now but on the recruitment side
For any sales person you have to first sell yourself. If they dont like you, you wont sell them shit and like somebody else said, listening to what they are saying back is very vital. Find out what they are interested in and just agree with everything they say, Once they "trust" and like you, then you can start your sales pitch. If they start to make excuses then just walk away cause you are wasting your time and even if it results in a lead it most prob wont follow up with a sale. Trying a hard sale to generate a lead wont work 9/10 cause they just want you away from the door. Selling is a numbers game so you "get to know" your buyer as quick as pos make the lead or sale and then go to the next buyer.
I do very well in recruitment and sales
although I do not do cold canvassing and havent done it in years, I still use similar tactics I used on the door.