Too many webmasters obsess over there Alexa ranking. The Alexa ranking is a meaningless value that is of no use in helping a site rank in the search engines. The search engines simply do not use it.
Alexa works out a traffic ranking based on the number of visits to a site from those that have the Alexa tool bar installed in their browser. That is more than enough to see how it can be faked and how easy it is to manipulate. A lower Alexa score means that you are getting more traffic.
The only use of Alexa is if you want to impress a potential advertiser about the traffic and any purchaser of advertising who knows what they are doing will not be impressed with it as they know the problems with it!
If you want to use the Alexa ranking, then use it for its entertainment value and do not take it seriously. If you really do want to improve the Alexa ranking, there are ways to do it.