Well, it's in finance niche. Highly competitive keyword. My site started to fall back in April with the Google Dewey Update. I also lost a number of backlinks. Partly the falt was my own. After getting married, I didn't give enough time to link building and writing fresh content. Going from #2 to #21 has been a HUGE experience in terms of daily earnings, SEO learning and emotionally. I have started an agressive link developemt compaign and I am glad to inform that today I can see the site sitting on #10, however, it moves to #21 ever now and then but I guess that's because all datacenters are yet to udpate. My backlinks in the webmaster tools have also increased and well that's helping.
As for the paid linking, I have NEVER bold/sold a link. I am very proud and happy of my previous positions in such a highly competitive niche without spending thousands of bucks on buying links/blogposts etc but sadly now, my competitors are doing far better than I am. Why? Because they keep buying links on high PR sites. I am amazed to see the budget of one of my competitors. A rough ballpark idea of his monthly link building budget is around $2000. He has far more unique hits than I do and he ranks very well on a number of different keywords because of his backlinks. I think I should report him now, it's getting wayyyy too difficult to deal with something like that. He is doing so well that TWO pages from his site show up when you do a search for a very competitive term (I am also ranking there). So you can imagine how much he must have spent buying links.
WHITEHAT SEO is not simple at all. It's not difficult but it's not simple by any means. You can understand the basics very easily and even though it will look easy, it's not. I have been doing this thing for around 3 years now and I believe I have to learn a lot more in order to call myself a professional SEO like Shawn or Jim Carter (don't know his real indian name) or Aaron Wall. Blackhat is a big NO NO. If you want to learn SEO, don't even consider thinking about learning blackhat SEO, but you should know about it so that you can deal with it if a competitor starts to do "everything blackhat" to get you penalized and off the high SERPs.