1. Make sure the age of your blog more than two weeks. Google sometimes reject blog that is new and under construction.
2. Enough blog content. Make sure you write an entry every day for a week. You can write two posts a day.
3. No pornographic content. Never include photos or images that seductive in your blog.
4. Use language that is approved by Google AdSense. Do not use language that is not understood by Google AdSense. Your account will not be approved because Google employees do not understand. For more information see here.
5. No ads. Do not put any ads on your blog when you apply for a Google AdSense account, including nuffnang or various other advertising companies to avoid misunderstandings that your blog already has deals with advertisers and not serious in the Google AdSense program. You can enter other advertisers after your account is approved.
Make sure the above checklist are complied, before you apply for Google AdSense. If you persist to apply before make sure things mentioned above you must be ready to receive e-mail rejection from Google AdSense.