Most of time students complain that they couldn't complete their objective paper; they were struck in one or another problem and wasted a lot of time. Some says that their guess went wrong and marks were deducted due to negative marking, some could not read paper completely and missed some easy questions etc.
I'll like to stress that objective paper solving is different from subjective paper. You don't need to study extra for objective questions but practice little bit.
Your guess in solving objective can bring you in difficulty but some intelligent/educated guess can add valuable marks to your score. Most of time objective questions have some hint in the form of multiple choices for the question.
Following can be used as guidelines for solving objective paper:
General Tips
Keep the structure of GATE in mind(25 Quest 1 Mark each, 30 Quest. 2 Marks each with 4 common data questions and 4 Linked Questions).
Plan your time. Allow more time for high point value questions; reserve time at the end to review your work, and for emergencies. I'll suggest following sequence, but you can keep as per your choice: 2 Marks question, Common Data Questions, Linked questions and then single mark questions.
Look the whole test over, skimming the quesitons and developing a general plan for your work. If any immediate thoughts come to you, jot them down in the margin
Start with the section of the test that will yield the most points, but begin working with the easiest questions to gain time for the more difficult ones and to warm up.
Work quickly, check your timing regularly, and adjust your speed when necessary.
Avoid reading into the questions. When you find yourself thinking along the lines of "this is too easy; there must be a trick..." mark the question and move on to another. Interpret questions literally.
Mark key words in every question. To help find the key words, ask yourself WHAT, WHO, WHERE, WHEN, and HOW?