Advertising on my site [Need help getting started]

[soundbarrierpro]

Hi, I'd like to start selling space on my site to advertisers.

Only problem is, I've never done it.

I'd like to know what the "Going rates" are and how you price them.
Is it per slot size like google adsense banners?
Do you add additional cost for video or pics and multiple lines of text?
Is there a base charge plus length of time the marketing company wants to advertise?

If anybody has any information, I'd greatly appreciate it.

Thank you