For whitehat methods, the soft-sell method seems to work best. I'm only working one account this way at the moment, and honestly conversions have been pretty slow, but not too bad. What I've done is built up an account pretty slowly within a niche, posting links to articles from a blog using the WP to Twitter plugin, as well as a few more personal tweets. Make sure the links are good information so they're used to clicking through. I've also used
http://twitterfeed.com to send out some newsfeeds on the niche's topic. Then I send out a link to an affiliate product review on the same blog no more than a couple of times a week.
I think if you did this with enough niche's you could make decent money.
