After you decide on the services or products you then want to get a domain name and website.
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I suggest that you do a search for "search engine ranking" so you can learn how to drive traffic to your site. Without visitors there will be very little sales.
The next step to generating traffic is to trade links with other sites. Avoid FFA's or link farms but find actual websites that won't compete with you but sell complimentary products and request and exchange of links with the webmaster. Link popularity is very important with search engines this may change but it is important as your site will likely improve in rankings the more links you have pointing to your site.
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