This is the art of having links pointing at your website from other websites, by having backlinks from other websites it will mean your website may be indexed more often.
– Get your website on search engines; add them on your own. Do not use an automated submission service.
– Create relationships with other webmasters and relevant site owners, this will allow you to have links on their website, preferably with good quality content assisting them.
– Get in forums and comment on relevant groups advising people to visit your website for free advice or assistance, ensure it is relevant and not spam.
– Add your website to bookmark sites such a Slashdot; do make sure you do not spam them though.
– Produce good articles and then submit them to websites with a link back crediting your work.