A website promotion cannot be organized by using internal methods of SEO only. At the moment the situation is that even the most interesting and convenient website with the unique content and correct internal structure can have no visitors if other websites do not consider it interesting (do not offer backlinks to it).

Therefore, external promotion is the focal point of SEO.
External promotion consists of links placing from certain resources to the website being promoted, publishing of various articles, news and many other things.

It should be noted that external promotion should be carried out by fair (white) methods only. In case of using various ‘grey-hat’ and ‘black-hat’ techniques of external promotion search engines can considerably penalize the website in the SERP or even ban it.

As far as the optimization expenses are considered – external promotion is that articles of expenditure which needs to be budgeted monthly since links to the website should be allocated constantly, and their effect grows eventually.