When you begin to take an examination you should do the easy questions first true or false?

That assertion is false. You are free to use any technique that you like; personally I prefer to answer questions in the order in which they appear. I would add that if a question is extremely difficult, you should not allow yourself to spend an excessive amount of time on it. You might want to just answer it as well as you can and move on, even if you have to choose an answer at random, but if you have extra time after answering the remaining questions, you can return to the really difficult one and think about whether you answered it correctly.