Selling To Everyone Means You Sell to No One
If you do not target your offer, it will confuse your customers. People are not patient. In a recent survey, 73% of people claimed to be "insanely busy". If you do not develop a target customer profile and appeal directly to them, you will lose customers. And they will never come back to your site again.

Web Flea Market: Buy a Web Site or Get a Grocery Coupon
People are selling Web Sites, classified advertising, pre-paid legal services, long distance phone cards, and reminder services via affiliate programs...All on the same Web Page!

Think about that the next time you go to your grocery store. Do they offer to sell you a Web Site with your pickles? Flea markets diminish the value of what you are selling. Most people who own these sites tell me they depend on selling a high volume of low price items. How do I know this is a doomed approach? Visit their sites and see if there is any life there.

Huge graphics that make your site take 30 seconds to open, which is all the time you have to sell your customer on staying.
The worst thing about computers is that they enable us to do things we just should not be doing. Graphic design is a skill; most people get some Paint program and have absolutely no sense of size, or what the graphic makes them look like. If you want to SCREAM AT YOUR AUDIENCE AND BE OBNOXIOUS, then use big graphics.

This site has XXXX number of visitors (How many bought?)
Does it really matter to anyone how many people visit your store? The sure sign that a store is visited often is the success and profits of the owner. All the rest is empty bragging.

Explaining what technology you use, frames, etc.
To this day it amazes me how people explain the technical design of their Web Page. If you use any reference to technology, you are distracting your customer. Keep it simple.

Download the following plug-ins to get this site working.
No one will spend ten minutes downloading the plug-in to see your cutesy message. Avoid plug-ins, with the possible exception of Real Audio.

No place to send an email, or gain a free report.
After spending all this time to create a site, most people forget to ask for inquiries. They just think people will work hard to contact them. Assume that a person will visit your site once, and never return unless you remind them to via email.