incrediBILL - 2:33 pm on May 9, 2013 (gmt 0)
Try reading the AdSense Policies:
AdSense for content: Publishers may place up to three AdSense for Content ad units on each page. Out of those three ad units, no more than one can be size 300x600. Publishers can place more than one of all ad sizes except the 300x600 on each page. In addition to three AdSense for Content ad units, publishers may also place up to three link units and two search boxes on each page. These policies apply to both desktop and high-end mobile optimized sites.
If you don't know what the rules are you're going to have a short-lived ride with AdSense as they cancel accounts for many reasons.
Not following the rules, especially if you haven't read them and don't know what they are, is usually the first step to being banned.
Please read the policies before proceeding.