I bet you could squeeze $10k a month out of that.

"Hi, I can give you 720,000 impressions/mo to weed smokers, would you like to advertise?"

So, how do I go about that? How much do I charge advertisers? I'm a complete n00b here.

Step 1: send a message. "Hi, I operate ThatHigh.com, which gets 720k pageviews a month. I saw that you advertise on HighTimes.com and thought my audience would also love your product. I'm currently looking for an advertiser for the 728x60 leaderboard on the home page. I'll split the traffic between you and one other advertiser, so you'll get about 360k impressions a month. I can offer it at $3000/month [try for about $10 CPM]. Let me know if that works for you."

Step 2: Send an invoice using Freshbooks or Blinksale.

Step 3: Install the creative using Google Ad Manager.

You can also try setting up zones through BuySellAds.com, and advertisers can buy directly when they visit your site. They take a cut, though.

Great advice, thanks alot.

You should post here once you do this and tell us how it goes. I'd be very interested to see how much you increase your revenue by.

Sure thing :-)