Can you advise me how to improve my web site's effectiveness?

There are a couple of things you may want to keep in mind when coding your site and researching your site's effectiveness.
Keep your title clear and attractive as much as possible. For example, "Welcome to Joe Blow's web site" does not exactly attract me. How about you? If your site is about automotives, keep your title specific to that subject.

Be sure to keep to the subject of your site. If your site is about sports, don't include news or links about that really cool MP3 player you saw advertised on TV a couple of days ago. Remember, your visitors are visiting your site for one reason: specific information.
Don't get too keyword happy. Include as many keywords as you can about your site's subject, but do not include completely irrelevant keywords, as it can actually decrease your search engine positioning.

 
Go ahead and visit search engines often. See which sites are listed first under the same keywords your site offers, and visit those sites. Look at that site's meta tags. What have they got that you don't? Keep in mind that some search engines will accept payment for higher result placement, so you may not be doing anything wrong except refusing to shell out dough.

 
Whip up business cards with your web site address printed on them, and don't be afraid to hand them out to those you come in contact with.
Create a signature within your e-mail program that will automatically write your name and web address at the bottom of every one of your e-mail messages. Versions of Microsoft Outlook and also Eudora can do this very easily. You may be surprised at how many folks will click on your link when they read your message.

Keeping to these coding techniques and practices can increase your web site's effectiveness. In addition, if you are running a business, you likely have a sense of the employee-customer relationship. With other sites (like this one), put yourself in the position of a businessman or woman wooing your customers. Get your name out there. Keep it out there. Be very benevolent in your correspondence with others on the Internet.