I know a lot about advertising partly because I sell ads on VegFamily and I also buy ads elsewhere.
The one thing I can tell you that is imperative is that you must be able to track the effectiveness of your ad or don't waste your time and money.
You want to track sales, not just clicks and click through rates.
I did an experiment on my own site. I had 5 different types of ads going for my book: banners, pictures, text, newsletter, etc.
My hubby helped me design a tracking code for every ad. I saw that my banners were getting a 1.2% click through rate. Excellent! But ZERO sales!! The image ad I have on my left side bar gets a .2% click through rate (low) but generates 50% of my sales! Bingo! If I hadn't tracked the actual sales from the ads, I might have gotten rid of the side bar ad and left the banners!
Before I ever pay for advertising I do some calculating. Here is my formula for how well I think something is going to work:
You need to know the cost of the ad, how many impressions you're going to get, and the average click through rate on those ads. Ask the company, they should tell you what rate to expect.
Okay, so let's say the cost of the ad is $50, for 10,000 impressions with a 1% click through rate.
You can expect 100 clicks on your ad. From there, you can expect a 1-2% conversion rate (sales). So that's 1-2 people buying the product you're advertising.
Now, ask yourself if the profit from 2 sales is worth more than the cost of the ad ($50). If it is... run the ad. If it isn't, it's too risky but you can try it. If it doesn't even come close to the cosst of your ad, then the price is too high and you won't make back your cost.
I wrote an article to help people who want to advertise on the web understand some of the nuances. It's called 8 Crucial Questions to Ask Any Company Before You Advertise On Their Website.http://www.vegfamily.com/advertising-questions.htm
I have a lot of knowledge in this area so if any one wants to pick my brain, please feel free. I'm so glad to see this new forum!