There are many, many factors that come into play when trying to get your website ranked well. I will cover some of the more important ones here:
-Have your website built by a professional web development company who has experience in search engine optimization (SEO)
-Make sure the company submits your new website to the major search engines when it is launched
-Create keyword-rich content for your website (in other words, if you are trying to sell Widgets in Nowhere, IN make sure your text talks about Widgets and mention Nowhere, IN throughout your website)
-Make sure your web development company completes your Meta data to current search engine standards
-Get other websites to link to your website- the more incoming links to your website the better!
-Make regular updates to the content on your website- keep your content fresh!
-Create unique content and publish it on the Internet, either through a Blog or through press releases
Search Engine Optimization companies can optimize your website after you launch it, but make sure you do your homework before hiring a company! Google's Webmaster Tools is a great resource:
Webmaster Tools
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