So, your ad has optimal placement, and you following my advice and removed the border and blended the background so it no longer has an outline, but is your job done? No, you still need to optimize the style of your ad.
You cannot change the font style or weight of your ads, however what you can do is change the font style on your own site to match that of your ads. Extreme? Maybe, but we're talking substantial money here.
What you're mainly trying to match is link styles so that your normal site links match the ad links. Both YPN & Adsense use the verdana font at different sizes, usually bolded. The size can vary depending on ad unit so you'll need to experiment with the ad units you use most and try to match them. They're also underlined, so if you do not use underlines you may wish to consider adding them.
These changes believe it or not can give a 10-20% increase in click through rate alone. Just for changing your font or font size. That is a big payoff for relatively little work.
Simply put, your description color should be the same color as the majority of the text on your site.
There are a variety of options here. You want your ads to blend in, and you accomplish that by using the steps already mentioned in this article, so you can if you want try to use the text link color to make it stand out.
A normal blue link is the most common link color on the Internet and you may wish to try that.
Another option is to change the link color with each page view. Using simple PHP you can associate colors with numbers and then generate a random number to pick a color. This should make the color change on every page view. The idea behind this is it keeps the interest of your uses through multiple page views.
The third option is to blend in the ad by using the same link color as the rest of your site. This often, but not always, works the best, and it certainly looks the best.
You may consider thinking about other colors, clashing colors, different colors. And while it is worth testing, in my own tests I found very little change no matter what random color I used.
I tested brown (blended for me), black, blue (the standard link color) and rainbow (rotating the color) in both the leaderboard and rectangle formats. In my tests both blue and brown performed roughly the same, with blue having only around a 1% edge on brown, black was around 5% less, and rainbow about 10% more. When I broke out the different colors of the rainbow for additional testing no one color stood out, meaning that it was the rainbow effect, and not any specific color, that was causing the increase in CTR.
The tests are not conclusive though as I could not isolate one variable, the advertisers. Advertisers change every week and that can obviously have an affect on your CTR. So I recommend you do your own tests on your site.
In the same vein as the rotation link color there is another thing you can try. On the 3rd, or 5th, or whatever page view you can do the opposite of what you'd normally do and make the ad clash as much as possible, put the background and border back, make them bright red or pink or another color that could clash with your design. Just make a big bright block of color. If your visitors have started ignoring your ads by that page view this might just prompt them to give it attention again.