There are four principal types of color schemes:

1. Blended. Set the ad unit’s background and border color to the match the page background color. Color your title either traditional hyperlink blue or the color you usually use for hyperlinks on your site.

2. Matching. Rather than matching the background color, match the most visible and important colors on your page. For example, if your logo is green, you might try coloring the ad unit's border and background the same green, then use the page background color as the ad unit’s text color. Typically, this makes the ad unit more noticeable than the blended technique.

3. Complementary. Rather than matching the most visible colors on the page, complement them. If you have trouble selecting completentary colors, searching for a color wheel or similar design tool will help. Leave the border hidden, and use the complementary colors for all the text, or use those complementary colors in the ad unit’s border and background.

4. Contrasting. This isn’t used as often, but there are publishers who find contrasting ad units perform the best. You may find a color wheel useful here as well. With this technique, you can choose to contrast colors near the ad unit, or the colors most prominent on the page. For maximum contrast, color the elements of the ad unit itself in contrasting colors.

When optimizing ad units for performance, location is one of the more volatile elements you might modify. Users' eye-travel habits change as their experience with the web grows, and page layouts vary so much that no universal rules exist for optimum location. That said, we'll look at a few suggested experiments that may produce helpful results for you.

Above content. Placing a leaderboard above the start of your main content is traditionally a highly visible location, and performs well. This location's effectiveness has diminished slightly for some publishers recently as some users skip ahead to content when a page first loads.

Such a prominent placement does not appeal to some publishers, who feel it detracts from their content, and lowers their users' satisfaction with their site. Some prefer to place their ads in less-obvious but still eye-catching places.

Selecting the eye-catching but less-obvious location, unless you can afford to commission an eye tracking study for your site, is a matter of anticipating where users look and when--or of monitoring which locations perform best.

Centered. Assuming that your primary page content is set in the center column, setting square and rectangle ads in this space will typically produce results. Set your ad units within the path of content, and allow the text or media to wrap around the space occupied by the ad unit.

Below the fold. Ads placed so low that users have to scroll to see them (this is called placing them "below the fold") tend to perform least well, with a few exceptions. If you have some useful functionality or eye-catching media near the footer, that may be a good place to put an extra ad unit.

On article pages people often want more information about the topic after they've finished reading a story. Placing an ad unit immediately following an article provides relevant links to readers who want to continue reading about the subject. The same idea applies to forums; people tend to go straight to the bottom of interesting threads to read the most recent posts, and ad performance can be affected by placing them there.

Layout hotspots. Ads placed near rich content and navigational aids usually do well because users are focused on those areas of a page.

Typically, users are somewhat more likely to read something that is about the same size as what they've just been reading. If your page content text is set between 9 and 11 points (many are), then that's often an effective size for your ad unit title and description. This may save users from having to squint or otherwise adjust to the font size. The URL can be smaller. This can add to the white space between the ads and make the ad unit look cleaner.

Wider ad formats tend to outperform their taller counterparts. Readers typically absorb information several words at a time. Wider lines of text let them comfortably read more text at a glance without having to scan down as many lines as they would with a narrower ad. Wider ad unit formats may also lessen the likelihood of readers leaving the ad unit altogether after skimming just a few lines or words.

Above all, use the format that best complements your pages. But if you want to experiment with wider units, try a wide rectangle or a wide skyscraper.

Many publishers prefer a cleaner look that comes without using a border. Combined with a blended color scheme, the ads appear less visually disruptive and may be less likely to inspire users to habitually ignore them. That said, advanced style settings can call attention to your ad units, so monitor closely how changes to borders affect your performance.

Use custom ad channels for each of your ad placements. For example, if you have differently formatted ad units running on different parts of your site, assign each of them to different channels and name the channels according the formatting changes. Watch your channel reports closely for indications of which changes affect performance, and make subtle alterations to top-performing units until you find the best combination of settings. You won't know what works best on your site until you repeatedly test changes this way.

In closing, keep testing formatting changes even after you've found combinations that seem to work best now. Users' habits change, your content will most likely change over time, and trends in advertising and design throughout the rest of the web will certainly change.