It boggles my mind that no one has mentioned www.link-vault.com or www.receivelinks.com. I use both but www.receivelinks.com is superior. Shocking how little people know. Neither costs a dime unless you need advanced features, which you don't unless you do it for a living like me. Feel free to PM me for free advice if you do use it.
Article writing is and submitting it to top article directories like ezine and go articles always work..
i agree with this one, but i think the best way is get a back link that related to your blog/site, so google will not loop your site as a spammer keyword.
Directory Submissions = Junk Forum Signatures = Junk Hardly if any juice is actually passed with these links. Don't waste your time. I would take one quality link of 10,000 junk links.