I have found that the best way to obtain respect in the classroom is to give the upmost respect to your students at all times. Even with students who are harder to earn, they should receive your full extent at all times. Never stoop to the level of the students if they are not giving you respect at that time. At the end of the day you are the educator and set the tone. If they are not expressing it to you then give them a chance to privately speak with you and or the director, then try again with a clean slate starting the next class. I love to say its ok to not love me today because I will be here tomorrow ready for you!