When it comes to promoting a book, the advantages of internet advertising over traditional print advertising can be summed up with the following acronym-rich equation: CPC - CPM = PPC. That's CMO-speak for expressing how much more cost effective cost-per-conversion analysis is to cost-per-thousand analysis.

With Pay Per Click advertising via Google and Overture, the cost of the ad is based upon the performance of the ad; however, the effectiveness of the ad is gauged by its conversion ratio. Thanks to tools provided by both Google and Overture, these conversion ratios can be calculated automatically.

Traditional print media, on the other hand, provides a CPM (cost per thousand) to demonstrate cost (value) of an ad. A certain number of people will see the ad (and believe me, this number is pie-in-the-sky, based upon circulation times "readership"). Therefore, the cost is X.

It's easy to recognize the advantages of pay per click advertising, especially when promoting a relatively small-ticket item such as a book, but before jumping head first into the PPC arena, review the following tips:

1) Be aware of the differences between Google and Overture

Google is the leading search engine at the moment, but their reach never exceeds their grasp. Overture technology, on the other hand, currently extends to Yahoo, AltaVista, CNN, Infospace, and others. Overture requires you to deposit money into an account in advance. Said account is then depleted based upon your campaign selection. Meanwhile, Google simply bills your credit card based upon your expenditures. Overture provides more intuitive and complete reporting functionality that enables you to analyze the effectiveness of keywords, but Google allows you to enter a maximum expenditure-per-day. This daily cap provides more control over your monthly spending while Overture's system simply draws money from the online account until depleted. This daily draw can vary substantially from one day to the next. Also, Overture requires you to keep 3 days of ?extra cash? on hand. Do you earn interest on the money you're loaning to Overture? Forget about it.

2) Be aware of the similarities

Both Google and Overture differentiate their paid clicks from their free, contextual algorithms, usually by featuring the ?sponsored? searches on a different part of the page and by highlighting them in a color box. Recently, Overture launched a new product, or search mechanism, whereby an advertiser can choose to be listed among the contextual content, also. That's kind of like paying for a meal after you've already eaten it.

Both services also experience infrequent, yet unexplained, ?spikes? that decimate your daily or monthly budget in a matter of minutes or hours. It's a little unnerving knowing that you could blow through $500 or $1000 in a matter of minutes with absolutely no recourse. Staffed to handle these anomalies, both services feature barely adequate customer service with representatives who often reply to such technical idiosyncrasies with hostile ambivalence. Sounds like an oxymoron, but it's not.

3) Start conservatively

That said, realize that pay-per-click campaigns are not an exact science and contain the potential to be ridiculously expensive if you're not careful. Start a campaign on either Google or Overture, but not both. Become familiar with the mechanics before launching full scale advertising campaigns on the other service.

4) Understand the mechanics

The way pay-for-performance works is simple. You bid on search terms, either words or phrases or a combination of both. Your webpage link then appears in search engine results relative to the price of the bid. If you're the highest bidder, your webpage appears at the absolute top of many search engines. Remember the frustration of typing in a search for your webpage and never finding your link? No longer!

5) Understand the advantages

Perhaps the best part of pay-for-performance advertising is the ?pay for performance? part. Unlike traditional advertising where you pay based upon the number of impressions, here, you only pay if people click on your link. In essence, they are pre-sold.

6) Select the appropriate keywords

Let's look at an example. Say you have published a mystery novel about the death of a land baron in Louisiana. Not exactly a new plot and yet millions of "whodunit" readers may be interested in reading it. Your solution? Open a pay-for-performance account and bid on search terms like "Louisiana Mystery Novel" and "Mystery Book Plantation" and other similar search terms. Counter-intuitively, the more specific the term, the better your campaign will perform, since very specific searches deliver very motivated buyers to your page. Since you're paying for each click, you want those browsers to buy! That's where "conversion" comes in to play.

7) Understand the disadvantages

You have to be very careful managing your bids and selecting your keywords, or pay-for-performance advertising can become ineffective. Do not bid on ridiculously vague and popular words like "book" or ?fiction? because you will never recoup your money. Instead, focus your search terms as specifically as possible.

It's only a matter of time before traditional print media finds some way to adopt this new method of cost-per-conversion and pay-for-performance advertising. Those who don't will die trying. Viva la digital revolution!