I particularly like the last point:
Customers paying late are a real pain. So don’t forget that you are a customer too. If you expect your customers to pay you promptly, then make sure you pay your suppliers promptly.I've read business writing by people who try and make their customers pay them yesterday, then don't pay their suppliers right up until the last minute, to keep the cash as long as possible. I don't like that.
I've dealt with one estate agent who used always to knock a percentage off his suppliers' bills when he paid them and argue it later if and when they noticed. Ouch ouch ouch.
Put it this way - having seen what he was like as a customer to his suppliers, I'd never buy a house through him. What goes around comes around.