I have 2 suggestions: 1 old and 1 new to this thread
The biggest secret is build a site you will enjoy doing first. Never build a site for money first.
Remember that search engines use spiders to read your site and spiders do two thing well....read html and read text.
Javascript, graphical buttons, flash animation and other non html code are all neat but hard for spiders to read.
Original content is indeed king. (till Universal Search takes over
)