Forum posting is sure and definite way of getting good quality backlinks. Blog comments are likely to be deleted after some time or even not accepted. So make it more on number of quality forums.
Directory Submissions is also one of the best ways and buying footer links on other websites works great too.
As many says: forum posting, forum comenting, blog posting and blog comentig are the best way. However, be sure that the links are "Do Follow" and the blogs or forums have a good PR. Also add your site on directories, or use online backlinkers
the best way to get backlinks free, is to post on do-follow blogs, forum signature, social bookmarking sites, link exchange with web 2.0 sites .... and so on. but focus on the web 2.0 sites and blog comments posting. Cheers.
Well to get back links is not an easy work but you can get it through this way. you have to do the following works:- unique,original and quality of post, post on the blog forums and promote your site every where.
Most SEO and business forums will let you have a signature link you just have to look for them. You can also look at forums that cover your industry.