This is another great article by Harish which tackles the ever present problem of how to manage online examinations. It is indeed a problem writing on a computer.
I have already written as to why it is bad to put a computer based exam here
Tips to make yourself comfortable for Jee Advanced (If at all you are very much confident of cracking Jee)
• Write Jee Mains online.(This is will be really helpful if you are focusing on Jee advanced,but be careful if you mess up Mains like I have done then it maybe a problem).
• Try to write BITSAT exam before the advanced exam.(Disadvantage-Writing after the Advanced helps you to actually decide whether you really want to write the exam Seriously and you can carry on preparing for the same.).
• Enrolling in some of the online test series held by coaching institutes (I guess Fiitjee has started online AITS,dont know about other coaching institute)
• Studying in front of your computer table(in a chair) with the computer off for atleast 3 hrs in a day(This will help you to sit for 3 long hours in a chair with limited movement).
• Solving a practice paper every Sunday Afternoon perhaps for 1 hr initially and then onwards gradually increasing the time as the exam comes close by(Afternoon slot is very crucial in JEE ,hence I would suggest you to try to write most of the exams in the afternoon,if you have time, then attempt both morning and afternoon).
• Solving papers online though you must not make it a habit and do it every alternate day as most of the online papers that you can avail,have bad paper standard and hence turns out to be a waste of time.
• Perhaps you can download a past Advanced paper(or even Mains as you will be needing for Mains as well) and solve that paper instead of solving a paper given by some online website.
All the best!