some methods are harder than others. the easy ones are forum and blog posting. i would not bother asking industry related websites for links its a waste of time, just do some of the things mentioned above. in terms of social bookmarking you will not get many do-follow back links but it can help drive traffic to your site
But what if I offer some sort of service, and I cant create any content? I can't write a blog about my life...
1) Forum Posting 2) Guest Blogging/Posting 3) Link Exchanges (Either paid or reciprocated) 4) Social Media Marketing 5) Blog Commenting (Mainly Do Follow + CommentLuv enabled Blogs)
may be: - wiki, gov, edu backlink - link from other relevan site - article submission link -link whell - i don't know