hhmmmm
I would agree with some of the previous comments, especially about looking professional.
Have you got a clipboard? No - go get one.
What do I have in it? - Customer forms, you need printed forms with sections for business name, address, what they require, frequency, special notes etc.
You also need quotation forms - forms with a little bit of information about your business, NOT YOU. The form should also have a couple of sections for what you are offering the client, what price it is being offered at and the frequencey.
Some people will think we go over the top with our paperwork but I can assure you, it sells us.
But you have to sell yourself too, after all, you are representing your business, you are its ambassador. For smaller businesses you can call in with your work UNIFORM on - not jeans and a t-shirt, I mean - trousers, boots and embroidered shirt/polo shirt.
Thats still not enough though, you must be polite - listen well, take notes and treat this as a formal business meeting.
Maybe this all sounds over the top but if you are like me, you are a business man - you never see Alan Sugar in jeans and a t-shirt, and out of all of us he's the one who can afford to dress slackily.
Last tip - never be afraid, some larger businesses will try and bully you into low quotes etc, stand your ground - it commands respect.
Coming back to the point about looking professional, if you look professional you will FEEL professional, if you look, feel and act professionally then you are professional - and prospective clients will see that - well done, the job is nearly yours.