i think, you can join CPA if you want to improve your earning.. because some people said that CPA is better than adsense...
One piece of advice - whichever way you approach it, whether Adsense, CPA, selling links, whatever - treat it like a business and not some yard sale. Know what you are doing, calculate your expenses, watch your income and market yourself. Be professional and you will reap the rewards.
Yes adsense is the only life time earning opportunity for everyone now a days if once our website is popular then just we have to do noting in adsense ...
affiliate marketing and the best way to make money on the internet if you have good method. for me, i make around $ 200 per month with adsense.
Adsense is the best for easy money once clicks starts to come in. CPA can make you a millionare if you can drive insane traffic to the offer.