Truly Entrecard brings live traffic and in somehow its free. You will be able to visit lots of blogs with different key topics and ideas. The mechanics is that you will view a blog with an Entrecard widget on it, and drop your card there, this will serve as a back link to your blog, a chance that the owner will visit your blog in return. Thus another way is to use the earned EC money to advertise to other site. EC money will be earn if you drop your card to other blogs and if other blogs advertise on your site.
Now, the key thing here, is to let user notice and try to “seduce” them to click and visit your blog through the card advertisement your placed on other blog. Here is a sample card I made for my blogs.
For this site I made a clear line of advertisement with eye catching font and color combination plus a seductive model background. Simple yet noticeable!