Smart but casual dress - clean shaven - nice aftershave and packet of mints
Although you may have butterflies take a deep breath and be confident - keep the pitch simple and straight forward - have a notepad and stick to your guns on price
Don't be too cheap !
You should get around 75% of what you quote - that will show you if you are about right for the area.
Do an hour to two hours and take a break before doing some more - always be positive polite and smile. Never per judge a house clean or dirty !
I've picked up really clean shiny properties just because the owner has decided that it's too much effort to keep them clean, likewise dirty places may just not have had a windy in that area for a while.
Big or small the worst they can say is no - if that happens just say thanks for your time - here's my card should you ever require my services.
Good luck - it's not easy to knock doors!
Darran