How to decrease alexa ranking of my website....its increases fastly.Give some suggessions as early as possible.
You may install Alexa Toolbar and recommend to do so to your friends and readers (everyone who visits your website). Or install Alexa widget at your website.
I would advice you to first go for the junk sites who offer good alexa rankings for free. Once, your rank has been stabilized to a certain number, then you start contacting or targeting the webmasters of most of the forums. All the webmasters do have alexa toolbar installed in their operating systems. Then as Maria said, mail all your friends and readers to download the alexa toolbar and open up your site atleast once everyday, which will certainly show you good results.
The easiest way is to download the toolbar and visit your site each day. Alternatively to get other users who have downloaded the toolbar post details of your site on webmaster forums and submit your site to various directories as the directory owners should have Alexa toolbar and when they view your site it should get an increase in ranking.
If you stay active in a webmaster forum like Digital Point and have a signature link, you will progress in Alexa quite well. People in the forum are more likely than most to have the Alexa tool bar installed. You can also post your site in the forum review section to get honest reviews and get the Alexa help as a bonus. My signature link site gets good traffic but tends to move up more when I am active in this forum.
You may purchase some service that could boost your alexa rank very fast, such as http://improvealexaranking.com.
I would expect it to help you from positions in the millions to a position in the top 400,000 quickly. If you are already better than 200,000 it will be a little slower going.
Descrease alexa is not difficult, you can use auto-surf, spam links, use social network... but the most important thing is content of your website.
When you climb from '10th best' to '2nd best' that is NOT a decrease in ranking, that is an increase in ranking.