Although I am not lover of blackhat, but all blackhat techniques is not literally black hat, you may take these tricky. Now what you should do it depends on you. Just dn't do any steps that violet the basic seo rules.
Blackhat isn't usually used for clients unless they are doing affiliate marketing or looking for quick cash. The results are fast and like all "get ranked quick" techniques get slapped down by Google almost as fast as it took to rank in the first place. Makes you wonder when article submissions will be deemed "blackhat" by the mighty G.
i agree if you plan to stay there for long, use white hat since it is proven to be effective in the long run...
It's probably worth knowing them so that you know to avoid it. i.e. you may inadvertantly use a black hat technique thinking it was perfectly legit method.
Take a look at my blog - I'll show you a way to get unlimited links from high authority sites including .gov and .edu. It's a black(ish) hat technique but you CANNOT be penalized for it. You are simply exploiting a vulnerability in PHP to put you links on other peoples sites.