there are a lot of variations and different opinions about how you should build links, there is not a right way to do it you just need to find your own way.. you start following someone guide but then you start making your own tweaks, just read the high quality campaing @ozz created and start from there.
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Then I'll use Article and Social networks as well as social bookmarks and Microblogs for Tier 2.
And then I use blog comments, image comments, guestbooks, and Indexer for Tier 3.