For our client: We took the top PPC terms based on conversion and worked these keywords into existing pages on the website. We also created new high-quality content-based pages from these conversion terms. This type of strategy can work very well in assisting overall conversions on the website and driving more revenue. We also conducted a large-scale keyword research project for the client which yielded in uncovering many areas of opportunity for content development and targeting. 
Hey Andreas, there are two main reasons I saw for suspending accounts - mean people and too many links. But they come to the same. On Yahoo Answers, like everywhere else, you have competition. They will flag your answer just so their answer would be chosen as the best. On the other hand, putting too many links in your answers can provoke the same thing. I usually put a link in every 3rd or 4th answer I post. And it is usually the best answer I can make. Glad you will try out the other sources, would love to see the results.
I don't generally think of my own list as a traffic source, because those are people that subscribed and keep coming back, mostly because of good content. This is more tutorial about where to get fresh traffic from in case a person is not using some of these sources already. Where have you guest posted, I haven't seen any, would like to read some of those :)
Let’s say that you are selling dog food. And most likely you will want the best traffic possible on the keyword “dog food”. Creating/building/earning all of your links with the same anchor text will get you in trouble. If you are having 600 links from which 400 use the anchor “dog food”, you might be facing a problem; it will surely raise a red flag to the search engines. And we all know what search engines do when they are getting these kinds of alarms: they begin applying penalties and move your websites so far from reach of the user that you will not be even listed in top 100. 

Beyond organic and direct traffic, you must understand the difference between all of your traffic sources and how traffic is classified. Most web analytics platforms, like Google Analytics, utilize an algorithm and flow chart based on the referring website or parameters set within the URL that determine the source of traffic. Here is a breakdown of all sources:
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