Through Forums Signature, Blog Posting, Blog commenting, Social Bookmarking, Articles Submission and very important steps if you can send bulk emails. Your website ranking will be increased quickly.
Yes, correct.. You said here already... You can also add, video marketing, press releases and so-on... You want more backlinks? Let me know and I can help.
First of all you should understand your competition, find your competitor and check their website backlinks and make sure that you can do all things that your competitor are doing.
The same method could be followed for back to back website also. The interlinking among the contents is greatly appreciated. And same other methods are to be applied, that means blog posting, commenting in the blog, creating forum and build backlink in there. And social bookmarking is also praised. And more than others the content should have good SEO.
Although, all the above said methods are available for increasing the backlinks but if you want to get the high ranking then youmust first analyze your competitors site and check their backlinks and then try to create the backlinks in the same sites in which your competitor has created backlinks.