1- Lack of content Not enough original content can be bad for your site and possibly land you into the supplemental results.

2- Duplicated content This is usually a problem with content management systems. Using the same amount of content with a few words rearranged can hurt. For example, if your site offered services for different cities and you used the same content for all and simply swaped out the cities; that would be seen as duplicated content.

3- Bad urls – Google just announced they can no longer read urls that end in id=123, which is great, however if your urls contain more than 2 query strings, you can still run into problems.

4- Hiding content – Believe it or not, this is still a problem. Some people try to get away with it by not making blend in exactly with the background (making the content 1 shade darker or lighter than the background color) or by making the content so small it can barely be read.

5- Exchanging links Linking to unrelated sites, especially while taking part in a link exchange, can be bad for your site. As Matt Cutts has stated here: http://www.mattcutts.com/blog/2006/05/, it’s best to stay away from link exchanges with sites that are not related. This might translate into your site not being fully indexed.

6- Backlinks and rankings – Many people have no idea what to do when they have a site built. They assume they can have it built and submit it to Google and that’s all it takes. Others are obsessed on numbers, thinking if they merely out-link their competition, they will rank better. Neither one of these are true.

7-Title and descriptions tags – Keeping title tags and or description tags the same throughout the site is bad. I have heard designers say, It keeps the site uniform. What it really does is place you in the supplemental index. Title and description tags should reflect what the page is about.

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