You have not provided a full picture of your stream with which you have proceeded further at least from class twelve and onwards. Is your post graduation from technical background related to some specific branch such as Mechanical, Electrical, Chemical etc or a mere post graduation or otherwise.
Considering your case as having a post graduation degree in the technical stream, I am briefing my suggestions-
1) Try to make an attractive resume with the datas as indicated above mentioning the details of degree of your graduation and post graduation reflecting the nature of the stream, details of the institution/ colleges etc. Include in your personal format whether you have had any inclination towards any extra curricular activities in your school or college days such as sports, debates etc. if you have won any medal at any stage in such activities, these should also be reflected in your format.
2) Regarding the scrutiny of your resume in TCS, HCL or any other IT sector, they would like to see consistency in your academic performance. By going through your achievements, only at the graduation stage, there is some shortfall of marks for which the members on the Board might ask you to provide a satisfactory response from your side.
3) Your selection would be based upon the three components to be held separately consisting of your written including current events, general knowledge, English and a technical paper followed by your interview with the members of the Board of the selection committee. The last one is the Medical Test which would follow only after the clearance of the former two stages.
4) Considering all these points mentioned, start preparing for the forthcoming test giving much importance to the basics taught in your areas. Please go through the such basics from the text books prescribed in the different stages of graduation and post graduation.
5) Remember in your Interview Session they would assess your communication skill and your patience in some difficult situations asking you very sensible questions.
6) If possible, take the help of a professional institute providing you necessary communication skills and other useful tips.
Hope your preparation should proceed accordingly and have the best of luck.