pay per click mistakes

http://www.practicalecommerce.com/articles/1110-Pay-per-click-Advertising-Top-6-Rookie-Mistakes

This article from "Practical ECommerce: Insights for Online Merchants" is a quick guide to the top 6 mistakes people make when doing pay per click advertising on the internet. I didn't really know too much about the topic anyway, but the one I really wouldn't have thought of would be rookie mistake number 5 to not have both search traffic and content traffic going on at the same time. If that puzzles you, the author explains himself in the comment section.

I read the author's comment on number 5 and I found it interesting. I never thought of the difference in advertising for people who are searching for something specific compared to someone who is just browsing around and how one should highlight price for the 'searching' customers and content for the 'browsing' customer. The rest of these tips seem pretty basic though but I guess a lot of people make them and it would be interesting to see how much money people lose on campaigns that feature mistakes most people think as obviously easy to avoid.
Als, I didn't know what negative keyword meant so i found this article http://www.practicalecommerce.com/articles/1086-Negative-Keywords-Improve-Pay-per-click-Performance-Save-Money

This website also talks about some pay per click mistakes when advertising a product or site on the internet.
http://www.payperclickuniverse.com/pay-per-click-search-engines-articles.php?article_id=83

Pay per click can be an effective tool for advertising, however, there can be some wastes that go into it as well. For instance, a mistake when doing pay per click advertising is to take the visitors to the appropriate site for the advertised product or service. If you think about it, the advertisement does no good if someone clicks on a link, and then has to click on more links. People won't have patience for this, and will not keep searching for the advertised link. Another key mistake not to make is to pay the extra money to be number one on the search hit list. The next few spots are just as effective, so this is money wasted to be slightly higher in a ranking. If these mistakes are considered, you will get more bang for your buck and utilize the positives of the pay per click system of advertising.