How to promote your site for free?

More and more often people start their sites or blogs! And if you make a site or blog only half of the business, then the second half will be much more difficult! The question arises: how to promote your site? Of course if you have a lot of money, it may be for you it will not be a problem! But if there is no money or there are very few of it! Or you just do not want to invest in website promotion in fundamentally?