From here, we can see that the Alexa for traffic measurement is inaccuracy. So yesterday i were thinking about this matter and trying to get the answer. Before i got the answer, actually I'm doing an experiment since yesterday. The experiment may take 1-2 weeks time to see the result.
Actually my experiment is not trying to gain more traffic to a blog, but trying to improve Alexa rank without increase the blog traffic. Maybe just 100-300 unique visitors per day, but can get below 50k.
This is tough. The experiment maybe fail or maybe success. But i hope i can success. Please don't ask me what's my experiment.
I can tell you that, after i googled for few hours, but i didn't find any web page / blog is sharing this tips.
Good luck to me! :D
Alexa Web Discovery Machine