Dear Sir/Madam, It will be very helpful if you just answer my questions. I have done my B.Sc[Physics,Maths,Computer] and now I am planning to do my M.Sc in mathematics. Can I go for IAS after my masters? Will it be beneficial for me? If I do my masters then meanwhile how should I prepare for the IAS exams? Is it necessary to join any coaching centers for IAS? If not then how to proceed? I will be very pleased if you sort out my questions.

Hi...
100% you are eligible for apperaing for IAS exam after completing your masters and always remeber that edcuation never goes in vain. Definitely, it will prove helpful to you in your IAS exam too as you will be more specialised in your subject area which in turn will prove helpful in preparing for UPSC exam. 
http://www.squidoo.com/iasguide 
Well, it canot be said that coaching is not good for IAS exam preparation as here you get to know about the exam, its pattern and important aspects etc .of the exam which is the toughest exam of the country, but at the same time it is also equally true that you can prepare for IAS exam on your own provided you are sure of what you are supposed to do. 
IN case, you choose to study on your own, do soem research beforehand beforer you start preparation and get equipped with all the information related to the exam. 
second, you must be update with current affairs of not only the country but also around the world for that start reading newspapers even read newspaper of last one year and magazine Competition Review. Choose 2 to 3 newspapers
!00% confident of the subjects you choose in the exam,start with the NCERT books of VI to XII std. 
Search online for the pattern of the exam and get familiar with it. 
These were very basic tips and the rest in on you. 
Make it your aim to achieve it and you will surely get it. 
Best of Luck