1. Many people are not getting good or complete advice. Often for example people don't understand all the concepts of Internet Marketing and having a website so they simply pay to have a website developed. Often this website may look good but it falls far short in the area of being "search engine friendly". This is typically because many businesses that deal with the web are very one track focused.

People need to get independent opinions from a knowledgeable person. Someone who doesn't have a biased agenda. Most businesses have a product or service they try to push customers toward because they make a greater profit on these items.

Many businesses that deal with the internet can be narrowly focused on their one main niche. They may do webpage design and development and for their ease they either knowingly or not don't consider other important attributes like optimizing the page for search engine placement. Some example are weblinks in java scripts. Search engines don't read these. Another example is the over use of images to display text on webpage. Search engines develop your webpages reputation based upon the words on the page. If the words are in images they can't be read by the search engines. A simple test to search for words is in your internet browser click on Edit and then click on Find and search on any suspect words.

2. People put too much emphasis on their Company name in their website title. The title should be geared toward keywords, etc. They don't take into account search engines and keywords and that starting out nobody is going to be searching on their Company Name.

3. People don't wisely choose their keywords or market. Planning here is key do some sample searches and see what comes up - who is your competition?

4. This is kind of a subset of number 3 above, lack of adequate planning. I.E What is the purpose of your webpage is it to sell them right there or perhaps gather their information for further use?

5. People don't either set up their website to collect names and leads (email list) or they just collect everyone's name in one big box. For example if you have several categories of interest on your site try to collect the person's email tied to their specific point of interest.

6. Over Targeting I see this problem all the time. People have a small website and they try to over target every keyword remotely associated with their website on each individual page. Each individual webpage should be targeted as much as possible. A variation of this is people try to optimize their sales page for good search engine ranking. A much better approach is optimized pages, which direct people to their sales page.

7. And of course they do a any number of things that are not friendly with search engines. (Here are just a few examples)

Like using frame pages incorrectly.

You are hosting your Web site at a free Web space provider.

Your Web site has a low link popularity.

Bonus Tip: When requesting links from other websites vary the linking text (title) you provide them, so that the linking text coming to your site isn't always the same. Think of it like this, in nature you would have a variance of linking texts. So if you do what is more natural, you should rank better with the search engines.