DOs:
-Follow the TOS of AdSense
-Best optimize your website, so you get more visitors from search engines, not from referrals
-Use proper keywords in your content. They will not only give you the good SEO, but will help AdSense to show relevant ads also which earn high
-Put a privacy policy page on your website. Use this link to generate a privacy policy page for your site: http://www.serprank.com/privacy-policy-generator/index.php
-Place the ads in the locations, where they would be seen easily by visitors, the more clicks you will get, more you will earn.
DONTs:
-Never click on your own ads or never ask friends to do so (follow the TOS of AdSense)
-Never alter the structure of your ads or never modify the code of your ads
-Never be tricky with AdSense to earn high. Be sincere
-Never access your AdSense account from public computers, if you do so and anyone else click on your ads later from that computer, Google will consider your own click and your account may be disapproved
-Never use any other ads which work like AdSense code
-Never buy traffic for your website
-Never put links on your webpages to any adult sites
-Never post adult content on your site
-Never miss the emails from AdSense, check your email account and act upon them, what they say. Sometimes, they ask you to take a survey, gently take it
-Never put much 3rd part plugins and widgets on your site, as they may contain hidden links to sites that AdSense don't like
Hope these few tips will help you starting your journey with AdSense, best of luck!!!