Design-business quesiton

I was always wondering, how does a average procedure of making affiliates in advertisement go, as far as your knowing goes, or if you have close experience.

F.I., if you have or know someone who has a attractive place for ads, how do you get clients to buy that space for certain amount of time?

Basically, is it “professional” to sent a email with a offer, or is it more common to call…and how to put it in words or text.

Is it basically “I got this and this space, it’s attractive, and I want xy cash” or negotiations look slightly different?