You've gotten some good advice, some shit advice and some fluff advice. Here is some real advice:
Wear khakis and a nice button down shirt, WITH A BELT and your shirt tucked in and pants pulled above your ass. Wear practical , brown or black leather shoes. No Chucks or Air Jordans .... etc.
The best days to cold call are Wednesday [before lunch] and Friday [the later in the day the better].
I have been in sales for 18 years. I have sold Kirby Vacuums door to door, Encyclopedia's , Newspaper subscriptions , and Culligan Water Filtration during college. After college I worked in the Secondary Mortgage Market (selling packages of shitty credit subprime mortgages to investors) until I said fuck the rat race and ran for my sanity. I would advise to not try and employ the typical "sales behavior" you have been offered as you will come across clumsy and bumbling.
Keep your intro short, sweet and to the point. Let them know who you are, what you're offering and attempt to identify a pain you can alleviate. Otherwise you're pissing in the wind.
You don't want to charge in after watching a 12 hour marathon of "Boiler Room" and "Glengarry Glen Ross" and attempt to "psycho fuck" your sales prospect to learn they have just filed for Bankruptcy and are closing their doors. What you want to employ is called "QUALIFYING" the prospect , versus dazing and confusing them with your verbal and psychological judo skills many salespeople utilize. Ask simple , pointed questions and let your prospect speak... if you're smart, you will let them sell themselves. This is the Aikido approach to sales I prefer and it works.
If you're cold calling over the phone, that is different game entirely and the approach needs to be aggressive as fuck! But this a convo for another time.