Well, I have marked some reasons of failure.
The main thing is our mind diver from one method to another method of making money online which is not good, we should focus on one only. For example, if you decided to earn from blogging then try your best to earn from it. It is true that from blogging people are earning thousands daily, you can also earn.
Other thing is not doing your main work and giving time for finding work more and more, if you are working as a freelancer and if you have some projects then your first duty is to finish these projects within time period so that you would get money from the client. I have found that I don't finish the work and I keep looking for other works also. it is not good.
Most of the time I pass in reading emails, visiting forums, blogs for finding work it is not good, I should do my work first and if I have free time then I should give time for other kind of work.