Increase your speed and answer questions correctly?

[doctortt]

What are some ways to increase your speed in solving a problem?

Would you rather complete all questions but get a low score due to incorrect answers or not able to complete all questions because you spend too much time to make sure the answers that you have entered are not from guessing?

[mbamaverick]

GMAT is the test of speed and accuracy. If you answer some questions correctly and leave some unanswered, the penalty for unanswered questions larger than wrong answered questions.