Even some days ago I was a younger student and my family was very angry on me. Why I spend so much time on the computer.... I had nothing to say at all. This way, the main problem students face is parents. They always want that we give full attention to our studies otherwise we will loose the both! But I say you should never sacrifice your full life by studying.
It is better that you stop earning when there is terminal exam near. But you keep it on. Specially if you have a blog, you update it everyday writing even 1 post. Never stop it! And you will earn insha Allah.
Side by side you can do some serveys in different websites searching on Google like www.MicroWorkers.com
And a great benefit in student life is friends! If you have many many friends you will get many many visitors in your daily. They can give new ideas! They can correct your spellings, concepts & color configuration.
Maximum students are able to start a blog but don't have enough information & article with them. They are not able to find the easy blogging topics which are probable to get more demand.
So these are the main problems which students face while earning. If you can show your parents that you are earning a healthy amount of money monthly & for this your education is not being harmed at all, then they will surely allow you to work online. But it will be very hard if you fail to blog for many times by hampering your
Acting may be necessary many times!!