GMAT

Here are some points on how to avoid being trapped:
Remember, the options in GMAT are designed to trap you. They are very similar and if you miss one small point in the question, you will end up with an incorrect option which you will feel is correct. So, it's always good to recheck your answer by re-reading your question. Make sure you are not missing/ignoring an important point.
Solve lots of questions and learn about the type/pattern of questions being asked. The more you solve, the more question patterns you'll learn about. While practising, if you get a question wrong, always learn how to solve it correctly. Ensure that you don't make the same mistakes again. Also, remember to keep your eyes open and be alert.
Learn to identify Pythagorean triplets, right angled triangles and ratio of sides (trigonometric ratios), etc. I can't stress more on the importance of remembering the formulas, tables, squared and cubes of numbers.

GMAT is exam conducted for getting into foreign universities.
Preparation can be of three types: self, self plus coaching, coaching. It depends on whether you are a working professional or a student. So, if you are working you have to prepare either by self-using the correspondence booklets or you can take the option of taking weekend coaching classes. Also, you can buy some famous books used for the preparation of MBA entrance exams. But if you are a student then you have a good amount of time to prepare. So you can use the correspondence course and books initially for self-preparation and later can join coaching classes for brushing up your preparation with added techniques. So, any MBA entrance exam has generally three sections- quantitative aptitude, logical reasoning & data interpretation and verbal reasoning along with the study of general current affairs. So, depending on your strengths, weakness and speed, prepare the three sections accordingly and nail the exam.
Note: GMAT section analytical writing assessment demands special attention. Practice as much as you can for this apart from the above preparation strategy.

Preparation can be of three types: self, self plus coaching, coaching. It depends on whether you are a working professional or a student. So, if you are working you have to prepare either by self-using the correspondence booklets or you can take the option of taking weekend coaching classes. Also, you can buy some famous books used for the preparation of MBA entrance exams. But if you are a student then you have a good amount of time to prepare. So you can use the correspondence course and books initially for self-preparation and later can join coaching classes for brushing up your preparation with added techniques. So, any MBA entrance exam has generally three sections- quantitative aptitude, logical reasoning & data interpretation and verbal reasoning along with the study of general current affairs. So, depending on your strengths, weakness and speed, prepare the three sections accordingly and nail the exam.
Both written and verbal communication is vital for GMAT, so prepare this part thoroughly.

There is nothing such thing called tougher to crack or easy to crack. This view depends upon the preparation of the exam you are giving. There are number of exams conducted in India for the MBA type courses. Exams like CAT, XAT, GMAT, MAT, IBSAT, NMAT, SNAP, etc. have some minor tweaking and variations apart from the main sections. Each of these exams has quantitative aptitude, Verbal reasoning, Logical reasoning and data interpretation, apart from GK or essay writing section in some of the exams. So, you have to prepare accordingly for these exams either by taking coaching classes or correspondence course or by self-preparation or by following recommended books. After you have prepared for the most difficult level questions, you may try to get some question banks for the specific exam you are targeting either offline mode i.e. books on exams or online mode I.e. free question banks websites or paid question banks for practice.