How to promote a website, if it is built from scratch. what steps to take to make it worth and to use it as an income source( means no selling of domain after getting traffic)

Gosh, that's a whole book. I'd recommend you take a look at the SEO Book Blog at:
SEO Book.com

It's more than just about SEO. It speaks about general internet marketing, packaging your ideas so that they sell, etc.

I should also point out too that developing and successfully marketing a website is a lot of hard work - it's not something to do just because you have a cool domain and can't get a good offer for it.

I would Like to add a bit in what Jeff said:
Your site must have:
# unique design
# SE Friendly (you can't make Google unhappy and expect to make a Living out of your Blog )
# Engrossing content.
# Social networking. especially when you start off with a new site, you do need help from others, like addition to blogrolls of popular blogs. THis surely helps in getting traffic.
# Keep the reader base intact and thinking about expanding it.

These are just basic things and if you want to start off with blog, problogger is also a good way to start OFF. He is particularly very good about blogs. Thanks for the SEO Book link Jeff.

blogs and article marketing often help to get the word out as well

wow great stuff guys!

I heard that using social advertising works wonders as well.

If you are going to promote your site from scratch then I suggest that you do your SEO first by doing forum signature and blog commenting. Just remember for some forum or blogs that has a “do follow” attribute.

Get as much traffic as possible by optimizing the content for search engines, and finding good content. Get more traffic by advertising it. After you've got the traffic, put in google ads, get in an ad network and so on.